define abstract in research methodology

Writing an Abstract for Your Research Paper

Definition and Purpose of Abstracts

An abstract is a short summary of your (published or unpublished) research paper, usually about a paragraph (c. 6-7 sentences, 150-250 words) long. A well-written abstract serves multiple purposes:

• an abstract lets readers get the gist or essence of your paper or article quickly, in order to decide whether to read the full paper;
• an abstract prepares readers to follow the detailed information, analyses, and arguments in your full paper;
• and, later, an abstract helps readers remember key points from your paper.

It’s also worth remembering that search engines and bibliographic databases use abstracts, as well as the title, to identify key terms for indexing your published paper. So what you include in your abstract and in your title are crucial for helping other researchers find your paper or article.

If you are writing an abstract for a course paper, your professor may give you specific guidelines for what to include and how to organize your abstract. Similarly, academic journals often have specific requirements for abstracts. So in addition to following the advice on this page, you should be sure to look for and follow any guidelines from the course or journal you’re writing for.

The Contents of an Abstract

Abstracts contain most of the following kinds of information in brief form. The body of your paper will, of course, develop and explain these ideas much more fully. As you will see in the samples below, the proportion of your abstract that you devote to each kind of information—and the sequence of that information—will vary, depending on the nature and genre of the paper that you are summarizing in your abstract. And in some cases, some of this information is implied, rather than stated explicitly. The Publication Manual of the American Psychological Association , which is widely used in the social sciences, gives specific guidelines for what to include in the abstract for different kinds of papers—for empirical studies, literature reviews or meta-analyses, theoretical papers, methodological papers, and case studies.

Here are the typical kinds of information found in most abstracts:

• the context or background information for your research; the general topic under study; the specific topic of your research
• the central questions or statement of the problem your research addresses
• what’s already known about this question, what previous research has done or shown
• the main reason(s) , the exigency, the rationale , the goals for your research—Why is it important to address these questions? Are you, for example, examining a new topic? Why is that topic worth examining? Are you filling a gap in previous research? Applying new methods to take a fresh look at existing ideas or data? Resolving a dispute within the literature in your field? . . .
• your research and/or analytical methods
• your main findings , results , or arguments
• the significance or implications of your findings or arguments.

Your abstract should be intelligible on its own, without a reader’s having to read your entire paper. And in an abstract, you usually do not cite references—most of your abstract will describe what you have studied in your research and what you have found and what you argue in your paper. In the body of your paper, you will cite the specific literature that informs your research.

When to Write Your Abstract

Although you might be tempted to write your abstract first because it will appear as the very first part of your paper, it’s a good idea to wait to write your abstract until after you’ve drafted your full paper, so that you know what you’re summarizing.

What follows are some sample abstracts in published papers or articles, all written by faculty at UW-Madison who come from a variety of disciplines. We have annotated these samples to help you see the work that these authors are doing within their abstracts.

Choosing Verb Tenses within Your Abstract

The social science sample (Sample 1) below uses the present tense to describe general facts and interpretations that have been and are currently true, including the prevailing explanation for the social phenomenon under study. That abstract also uses the present tense to describe the methods, the findings, the arguments, and the implications of the findings from their new research study. The authors use the past tense to describe previous research.

The humanities sample (Sample 2) below uses the past tense to describe completed events in the past (the texts created in the pulp fiction industry in the 1970s and 80s) and uses the present tense to describe what is happening in those texts, to explain the significance or meaning of those texts, and to describe the arguments presented in the article.

The science samples (Samples 3 and 4) below use the past tense to describe what previous research studies have done and the research the authors have conducted, the methods they have followed, and what they have found. In their rationale or justification for their research (what remains to be done), they use the present tense. They also use the present tense to introduce their study (in Sample 3, “Here we report . . .”) and to explain the significance of their study (In Sample 3, This reprogramming . . . “provides a scalable cell source for. . .”).

Sample Abstract 1

From the social sciences.

Reporting new findings about the reasons for increasing economic homogamy among spouses

Gonalons-Pons, Pilar, and Christine R. Schwartz. “Trends in Economic Homogamy: Changes in Assortative Mating or the Division of Labor in Marriage?” Demography , vol. 54, no. 3, 2017, pp. 985-1005.

Sample Abstract 2

From the humanities.

Analyzing underground pulp fiction publications in Tanzania, this article makes an argument about the cultural significance of those publications

Emily Callaci. “Street Textuality: Socialism, Masculinity, and Urban Belonging in Tanzania’s Pulp Fiction Publishing Industry, 1975-1985.” Comparative Studies in Society and History , vol. 59, no. 1, 2017, pp. 183-210.

Sample Abstract/Summary 3

From the sciences.

Reporting a new method for reprogramming adult mouse fibroblasts into induced cardiac progenitor cells

Lalit, Pratik A., Max R. Salick, Daryl O. Nelson, Jayne M. Squirrell, Christina M. Shafer, Neel G. Patel, Imaan Saeed, Eric G. Schmuck, Yogananda S. Markandeya, Rachel Wong, Martin R. Lea, Kevin W. Eliceiri, Timothy A. Hacker, Wendy C. Crone, Michael Kyba, Daniel J. Garry, Ron Stewart, James A. Thomson, Karen M. Downs, Gary E. Lyons, and Timothy J. Kamp. “Lineage Reprogramming of Fibroblasts into Proliferative Induced Cardiac Progenitor Cells by Defined Factors.” Cell Stem Cell , vol. 18, 2016, pp. 354-367.

Sample Abstract 4, a Structured Abstract

Reporting results about the effectiveness of antibiotic therapy in managing acute bacterial sinusitis, from a rigorously controlled study

Note: This journal requires authors to organize their abstract into four specific sections, with strict word limits. Because the headings for this structured abstract are self-explanatory, we have chosen not to add annotations to this sample abstract.

Wald, Ellen R., David Nash, and Jens Eickhoff. “Effectiveness of Amoxicillin/Clavulanate Potassium in the Treatment of Acute Bacterial Sinusitis in Children.” Pediatrics , vol. 124, no. 1, 2009, pp. 9-15.

“OBJECTIVE: The role of antibiotic therapy in managing acute bacterial sinusitis (ABS) in children is controversial. The purpose of this study was to determine the effectiveness of high-dose amoxicillin/potassium clavulanate in the treatment of children diagnosed with ABS.

METHODS : This was a randomized, double-blind, placebo-controlled study. Children 1 to 10 years of age with a clinical presentation compatible with ABS were eligible for participation. Patients were stratified according to age (<6 or ≥6 years) and clinical severity and randomly assigned to receive either amoxicillin (90 mg/kg) with potassium clavulanate (6.4 mg/kg) or placebo. A symptom survey was performed on days 0, 1, 2, 3, 5, 7, 10, 20, and 30. Patients were examined on day 14. Children’s conditions were rated as cured, improved, or failed according to scoring rules.

RESULTS: Two thousand one hundred thirty-five children with respiratory complaints were screened for enrollment; 139 (6.5%) had ABS. Fifty-eight patients were enrolled, and 56 were randomly assigned. The mean age was 6630 months. Fifty (89%) patients presented with persistent symptoms, and 6 (11%) presented with nonpersistent symptoms. In 24 (43%) children, the illness was classified as mild, whereas in the remaining 32 (57%) children it was severe. Of the 28 children who received the antibiotic, 14 (50%) were cured, 4 (14%) were improved, 4(14%) experienced treatment failure, and 6 (21%) withdrew. Of the 28children who received placebo, 4 (14%) were cured, 5 (18%) improved, and 19 (68%) experienced treatment failure. Children receiving the antibiotic were more likely to be cured (50% vs 14%) and less likely to have treatment failure (14% vs 68%) than children receiving the placebo.

CONCLUSIONS : ABS is a common complication of viral upper respiratory infections. Amoxicillin/potassium clavulanate results in significantly more cures and fewer failures than placebo, according to parental report of time to resolution.” (9)

Some Excellent Advice about Writing Abstracts for Basic Science Research Papers, by Professor Adriano Aguzzi from the Institute of Neuropathology at the University of Zurich:

Academic and Professional Writing

This is an accordion element with a series of buttons that open and close related content panels.

Analysis Papers

Reading Poetry

A Short Guide to Close Reading for Literary Analysis

Using Literary Quotations

Play Reviews

Writing a Rhetorical Précis to Analyze Nonfiction Texts

Incorporating Interview Data

Grant Proposals

Planning and Writing a Grant Proposal: The Basics

Additional Resources for Grants and Proposal Writing

Job Materials and Application Essays

Writing Personal Statements for Ph.D. Programs

• Before you begin: useful tips for writing your essay
• Guided brainstorming exercises
• Get more help with your essay
• Frequently Asked Questions

Resume Writing Tips

CV Writing Tips

Cover Letters

Business Letters

Proposals and Dissertations

Resources for Proposal Writers

Resources for Dissertators

Research Papers

Planning and Writing Research Papers

Quoting and Paraphrasing

Writing Annotated Bibliographies

Creating Poster Presentations

Thank-You Notes

Advice for Students Writing Thank-You Notes to Donors

Reading for a Review

Critical Reviews

Writing a Review of Literature

Scientific Reports

Scientific Report Format

Sample Lab Assignment

Writing for the Web

Writing an Effective Blog Post

Writing for Social Media: A Guide for Academics

• USC Libraries
• Research Guides

Organizing Your Social Sciences Research Paper

• 3. The Abstract
• Purpose of Guide
• Design Flaws to Avoid
• Independent and Dependent Variables
• Glossary of Research Terms
• Reading Research Effectively
• Narrowing a Topic Idea
• Broadening a Topic Idea
• Extending the Timeliness of a Topic Idea
• Academic Writing Style
• Applying Critical Thinking
• Choosing a Title
• Making an Outline
• Paragraph Development
• Research Process Video Series
• Executive Summary
• The C.A.R.S. Model
• Background Information
• The Research Problem/Question
• Theoretical Framework
• Citation Tracking
• Content Alert Services
• Evaluating Sources
• Primary Sources
• Secondary Sources
• Tiertiary Sources
• Scholarly vs. Popular Publications
• Qualitative Methods
• Quantitative Methods
• Insiderness
• Using Non-Textual Elements
• Limitations of the Study
• Common Grammar Mistakes
• Writing Concisely
• Avoiding Plagiarism
• Footnotes or Endnotes?
• Further Readings
• Generative AI and Writing
• USC Libraries Tutorials and Other Guides
• Bibliography

An abstract summarizes, usually in one paragraph of 300 words or less, the major aspects of the entire paper in a prescribed sequence that includes: 1) the overall purpose of the study and the research problem(s) you investigated; 2) the basic design of the study; 3) major findings or trends found as a result of your analysis; and, 4) a brief summary of your interpretations and conclusions.

Writing an Abstract. The Writing Center. Clarion University, 2009; Writing an Abstract for Your Research Paper. The Writing Center, University of Wisconsin, Madison; Koltay, Tibor. Abstracts and Abstracting: A Genre and Set of Skills for the Twenty-first Century . Oxford, UK: Chandos Publishing, 2010;

Importance of a Good Abstract

Sometimes your professor will ask you to include an abstract, or general summary of your work, with your research paper. The abstract allows you to elaborate upon each major aspect of the paper and helps readers decide whether they want to read the rest of the paper. Therefore, enough key information [e.g., summary results, observations, trends, etc.] must be included to make the abstract useful to someone who may want to examine your work.

How do you know when you have enough information in your abstract? A simple rule-of-thumb is to imagine that you are another researcher doing a similar study. Then ask yourself: if your abstract was the only part of the paper you could access, would you be happy with the amount of information presented there? Does it tell the whole story about your study? If the answer is "no" then the abstract likely needs to be revised.

Farkas, David K. “A Scheme for Understanding and Writing Summaries.” Technical Communication 67 (August 2020): 45-60;  How to Write a Research Abstract. Office of Undergraduate Research. University of Kentucky; Staiger, David L. “What Today’s Students Need to Know about Writing Abstracts.” International Journal of Business Communication January 3 (1966): 29-33; Swales, John M. and Christine B. Feak. Abstracts and the Writing of Abstracts . Ann Arbor, MI: University of Michigan Press, 2009.

Structure and Writing Style

I.  Types of Abstracts

To begin, you need to determine which type of abstract you should include with your paper. There are four general types.

Critical Abstract A critical abstract provides, in addition to describing main findings and information, a judgment or comment about the study’s validity, reliability, or completeness. The researcher evaluates the paper and often compares it with other works on the same subject. Critical abstracts are generally 400-500 words in length due to the additional interpretive commentary. These types of abstracts are used infrequently.

Descriptive Abstract A descriptive abstract indicates the type of information found in the work. It makes no judgments about the work, nor does it provide results or conclusions of the research. It does incorporate key words found in the text and may include the purpose, methods, and scope of the research. Essentially, the descriptive abstract only describes the work being summarized. Some researchers consider it an outline of the work, rather than a summary. Descriptive abstracts are usually very short, 100 words or less. Informative Abstract The majority of abstracts are informative. While they still do not critique or evaluate a work, they do more than describe it. A good informative abstract acts as a surrogate for the work itself. That is, the researcher presents and explains all the main arguments and the important results and evidence in the paper. An informative abstract includes the information that can be found in a descriptive abstract [purpose, methods, scope] but it also includes the results and conclusions of the research and the recommendations of the author. The length varies according to discipline, but an informative abstract is usually no more than 300 words in length.

Highlight Abstract A highlight abstract is specifically written to attract the reader’s attention to the study. No pretense is made of there being either a balanced or complete picture of the paper and, in fact, incomplete and leading remarks may be used to spark the reader’s interest. In that a highlight abstract cannot stand independent of its associated article, it is not a true abstract and, therefore, rarely used in academic writing.

II.  Writing Style

Use the active voice when possible , but note that much of your abstract may require passive sentence constructions. Regardless, write your abstract using concise, but complete, sentences. Get to the point quickly and always use the past tense because you are reporting on a study that has been completed.

Abstracts should be formatted as a single paragraph in a block format and with no paragraph indentations. In most cases, the abstract page immediately follows the title page. Do not number the page. Rules set forth in writing manual vary but, in general, you should center the word "Abstract" at the top of the page with double spacing between the heading and the abstract. The final sentences of an abstract concisely summarize your study’s conclusions, implications, or applications to practice and, if appropriate, can be followed by a statement about the need for additional research revealed from the findings.

Composing Your Abstract

Although it is the first section of your paper, the abstract should be written last since it will summarize the contents of your entire paper. A good strategy to begin composing your abstract is to take whole sentences or key phrases from each section of the paper and put them in a sequence that summarizes the contents. Then revise or add connecting phrases or words to make the narrative flow clearly and smoothly. Note that statistical findings should be reported parenthetically [i.e., written in parentheses].

Before handing in your final paper, check to make sure that the information in the abstract completely agrees with what you have written in the paper. Think of the abstract as a sequential set of complete sentences describing the most crucial information using the fewest necessary words. The abstract SHOULD NOT contain:

• A catchy introductory phrase, provocative quote, or other device to grab the reader's attention,
• Lengthy background or contextual information,
• Redundant phrases, unnecessary adverbs and adjectives, and repetitive information;
• Acronyms or abbreviations,
• References to other literature [say something like, "current research shows that..." or "studies have indicated..."],
• Using ellipticals [i.e., ending with "..."] or incomplete sentences,
• Jargon or terms that may be confusing to the reader,
• Citations to other works, and
• Any sort of image, illustration, figure, or table, or references to them.

Abstract. Writing Center. University of Kansas; Abstract. The Structure, Format, Content, and Style of a Journal-Style Scientific Paper. Department of Biology. Bates College; Abstracts. The Writing Center. University of North Carolina; Borko, Harold and Seymour Chatman. "Criteria for Acceptable Abstracts: A Survey of Abstracters' Instructions." American Documentation 14 (April 1963): 149-160; Abstracts. The Writer’s Handbook. Writing Center. University of Wisconsin, Madison; Hartley, James and Lucy Betts. "Common Weaknesses in Traditional Abstracts in the Social Sciences." Journal of the American Society for Information Science and Technology 60 (October 2009): 2010-2018; Koltay, Tibor. Abstracts and Abstracting: A Genre and Set of Skills for the Twenty-first Century. Oxford, UK: Chandos Publishing, 2010; Procter, Margaret. The Abstract. University College Writing Centre. University of Toronto; Riordan, Laura. “Mastering the Art of Abstracts.” The Journal of the American Osteopathic Association 115 (January 2015 ): 41-47; Writing Report Abstracts. The Writing Lab and The OWL. Purdue University; Writing Abstracts. Writing Tutorial Services, Center for Innovative Teaching and Learning. Indiana University; Koltay, Tibor. Abstracts and Abstracting: A Genre and Set of Skills for the Twenty-First Century . Oxford, UK: 2010; Writing an Abstract for Your Research Paper. The Writing Center, University of Wisconsin, Madison.

Writing Tip

Never Cite Just the Abstract!

Citing to just a journal article's abstract does not confirm for the reader that you have conducted a thorough or reliable review of the literature. If the full-text is not available, go to the USC Libraries main page and enter the title of the article [NOT the title of the journal]. If the Libraries have a subscription to the journal, the article should appear with a link to the full-text or to the journal publisher page where you can get the article. If the article does not appear, try searching Google Scholar using the link on the USC Libraries main page. If you still can't find the article after doing this, contact a librarian or you can request it from our free i nterlibrary loan and document delivery service .

• << Previous: Research Process Video Series
• Next: Executive Summary >>
• Last Updated: May 15, 2024 9:53 AM
• URL: https://libguides.usc.edu/writingguide

• Departments and Units
• Majors and Minors
• LSA Course Guide
• LSA Gateway

Search: {{$root.lsaSearchQuery.q}}, Page {{$root.page}}

• Accessibility
• Undergraduates
• Instructors
• Alums & Friends

• ★ Writing Support
• Minor in Writing
• First-Year Writing Requirement
• Transfer Students
• Writing Guides
• Peer Writing Consultant Program
• Upper-Level Writing Requirement
• Writing Prizes
• International Students
• ★ The Writing Workshop
• Dissertation ECoach
• Fellows Seminar
• Dissertation Writing Groups
• Rackham / Sweetland Workshops
• Dissertation Writing Institute
• Guides to Teaching Writing
• Teaching Support and Services
• Support for FYWR Courses
• Support for ULWR Courses
• Writing Prize Nominating
• Alums Gallery
• Commencement
• Giving Opportunities
• What Exactly is an Abstract?
• How Do I Make Sure I Understand an Assignment?
• How Do I Decide What I Should Argue?
• How Can I Create Stronger Analysis?
• How Do I Effectively Integrate Textual Evidence?
• How Do I Write a Great Title?
• How Do I Present Findings From My Experiment in a Report?
• What is a Run-on Sentence & How Do I Fix It?
• How Do I Check the Structure of My Argument?
• How Do I Write an Intro, Conclusion, & Body Paragraph?
• How Do I Incorporate Quotes?
• How Can I Create a More Successful Powerpoint?
• How Can I Create a Strong Thesis?
• How Can I Write More Descriptively?
• How Do I Incorporate a Counterargument?
• How Do I Check My Citations?

See the bottom of the main Writing Guides page for licensing information.

What Exactly is an Abstract, and How Do I Write One?

An abstract is a short summary of your completed research. It is intended to describe your work without going into great detail. Abstracts should be self-contained and concise, explaining your work as briefly and clearly as possible. Different disciplines call for slightly different approaches to abstracts, as will be illustrated by the examples below, so it would be wise to study some abstracts from your own field before you begin to write one.

General Considerations

Probably the most important function of an abstract is to help a reader decide if he or she is interested in reading your entire publication. For instance, imagine that you’re an undergraduate student sitting in the library late on a Friday night. You’re tired, bored, and sick of looking up articles about the history of celery. The last thing you want to do is reading an entire article only to discover it contributes nothing to your argument. A good abstract can solve this problem by indicating to the reader if the work is likely to be meaningful to his or her particular research project. Additionally, abstracts are used to help libraries catalogue publications based on the keywords that appear in them.

An effective abstract will contain several key features:

• Motivation/problem statement: Why is your research/argument important? What practical, scientific, theoretical or artistic gap is your project filling?
• Methods/procedure/approach: What did you actually do to get your results? (e.g. analyzed 3 novels, completed a series of 5 oil paintings, interviewed 17 students)
• Results/findings/product: As a result of completing the above procedure, what did you learn/invent/create?
• Conclusion/implications: What are the larger implications of your findings, especially for the problem/gap identified previously? Why is this research valuable?

In Practice

Let’s take a look at some sample abstracts, and see where these components show up. To give you an idea of how the author meets these “requirements” of abstract writing, the various features have been color-coded to correspond with the numbers listed above. The general format of an abstract is largely predictable, with some discipline-based differences. One type of abstract not discussed here is the “Descriptive Abstract,” which only summarizes and explains existing research, rather than informing the reader of a new perspective. As you can imagine, such an abstract would omit certain components of our four-colored model.

SAMPLE ABSTRACTS

ABSTRACT #1: History / Social Science

"Their War": The Perspective of the South Vietnamese Military in Their Own Words Author: Julie Pham

Despite the vast research by Americans on the Vietnam War, little is known about the perspective of South Vietnamese military, officially called the Republic of Vietnam Armed Forces (RVNAF). The overall image that emerges from the literature is negative: lazy, corrupt, unpatriotic, apathetic soldiers with poor fighting spirits. This study recovers some of the South Vietnamese military perspective for an American audience through qualititative interviews with 40 RVNAF veterans now living in San José, Sacramento, and Seattle, home to three of the top five largest Vietnamese American communities in the nation. An analysis of these interviews yields the veterans' own explanations that complicate and sometimes even challenge three widely held assumptions about the South Vietnamese military: 1) the RVNAF was rife with corruption at the top ranks, hurting the morale of the lower ranks; 2) racial relations between the South Vietnamese military and the Americans were tense and hostile; and 3) the RVNAF was apathetic in defending South Vietnam from communism. The stories add nuance to our understanding of who the South Vietnamese were in the Vietnam War. This study is part of a growing body of research on non-American perspectives of the war. In using a largely untapped source of Vietnamese history—oral histories with Vietnamese immigrants—this project will contribute to future research on similar topics.

That was a fairly basic abstract that allows us to examine its individual parts more thoroughly.

Motivation/problem statement: The author identifies that previous research has been done about the Vietnam War, but that it has failed to address the specific topic of South Vietnam’s military. This is good because it shows how the author’s research fits into the bigger picture. It isn’t a bad thing to be critical of other research, but be respectful from an academic standpoint (i.e. “Previous researchers are stupid and don’t know what they’re talking about” sounds kind of unprofessional).

Methods/procedure/approach: The author does a good job of explaining how she performed her research, without giving unnecessary detail. Noting that she conducted qualitative interviews with 40 subjects is significant, but she wisely does not explicitly state the kinds of questions asked during the interview, which would be excessive.

Results/findings/product: The results make good use of numbering to clearly indicate what was ascertained from the research—particularly useful, as people often just scan abstracts for the results of an experiment.

Conclusion/implications: Since this paper is historical in nature, its findings may be hard to extrapolate to modern-day phenomena, but the author identifies the importance of her work as part of a growing body of research, which merits further investigation. This strategy functions to encourage future research on the topic.

ABSTRACT #2: Natural Science “A Lysimeter Study of Grass Cover and Water Table Depth Effects on Pesticide Residues in Drainage Water” Authors: A. Liaghat, S.O. Prasher

A study was undertaken to investigate the effect of soil and grass cover, when integrated with water table management (subsurface drainage and controlled drainage), in reducing herbicide residues in agricultural drainage water. Twelve PVC lysimeters, 1 m long and 450 mm diameter, were packed with a sandy soil and used to study the following four treatments: subsurface drainage, controlled drainage, grass (sod) cover, and bare soil. Contaminated water containing atrazine, metolachlor, and metribuzin residues was applied to the lysimeters and samples of drain effluent were collected. Significant reductions in pesticide concentrations were found in all treatments. In the first year, herbicide levels were reduced significantly (1% level), from an average of 250 mg/L to less than 10 mg/L . In the second year, polluted water of 50 mg/L, which is considered more realistic and reasonable in natural drainage waters, was applied to the lysimeters and herbicide residues in the drainage waters were reduced to less than 1 mg/L. The subsurface drainage lysimeters covered with grass proved to be the most effective treatment system.

Motivation/problem statement: Once again, we see that the problem—more like subject of study —is stated first in the abstract. This is normal for abstracts, in that you want to include the most important information first. The results may seem like the most important part of the abstract, but without mentioning the subject, the results won’t make much sense to readers. Notice that the abstract makes no references to other research, which is fine. It is not obligatory to cite other publications in an abstract, and in fact, doing so might distract your reader from YOUR experiment. Either way, it is likely that other sources will surface in your paper’s discussion/conclusion.

Methods/procedure/approach: Notice that the authors include pertinent numbers and figures in describing their methods. An extended description of the methods would probably include a long list of numerical values and conditions for each experimental trial, so it is important to include only the most important values in your abstract—ones that might make your study unique. Additionally, we see that a methodological description appears in two different parts of the abstract. This is fine. It may work better to explain your experiment by more closely connecting each method to its result. One last point: the author doesn’t take time to define—or give any background information about—“atrazine,” “metalachlor,” “lysimeter,” or “metribuzin.” This may be because other ecologists know what these are, but even if that’s not the case, you shouldn’t take time to define terms in your abstract.

Results/findings/product: Similar to the methods component of the abstract, you want to condense your findings to include only the major result of the experiment. Again, this study focused on two major trials, so both trials and both major results are listed. A particularly important word to consider when sharing results in an abstract is “significant.” In statistics, “significant” means roughly that your results were not due to chance. In your paper, your results may be hundreds of words long, and involve dozens of tables and graphs, but ultimately, your reader only wants to know: “What was the main result, and was that result significant?” So, try to answer both these questions in the abstract.

Conclusion/implications: This abstract’s conclusion sounds more like a result: “…lysimeters covered with grass were found to be the most effective treatment system.” This may seem incomplete, since it does not explain how this system could/should/would be applied to other situations, but that’s okay. There is plenty of space for addressing those issues in the body of the paper.

ABSTRACT #3: Philosophy / Literature [Note: Many papers don’t precisely follow the previous format, since they do not involve an experiment and its methods. Nonetheless, they typically rely on a similar structure.]

“Participatory Legitimation: A Reply to Arash Abizadeh” Author: Eric Schmidt, Louisiana State University, 2011

Arash Abizadeh’s argument against unilateral border control relies on his unbounded demos thesis, which is supported negatively by arguing that the ‘bounded demos thesis’ is incoherent. The incoherency arises for two reasons: (1) Democratic principles cannot be brought to bear on matters (border control) logically prior to the constitution of a group, and (2), the civic definition of citizens and non-citizens creates an ‘externality problem’ because the act of definition is an exercise of coercive power over all persons. The bounded demos thesis is rejected because the “will of the people” fails to legitimate democratic political order because there can be no pre-political political will of the people. However, I argue that “the will of the people” can be made manifest under a robust understanding of participatory legitimation, which exists concurrently with the political state, and thus defines both its borders and citizens as bounded , rescuing the bounded demos thesis and compromising the rest of Abizadeh’s article.

This paper may not make any sense to someone not studying philosophy, or not having read the text being critiqued. However, we can still see where the author separates the different components of the abstract, even if we don’t understand the terminology used.

Motivation/problem statement: The problem is not really a problem, but rather another person’s belief on a subject matter. For that reason, the author takes time to carefully explain the exact theory that he will be arguing against.

Methods/procedure/approach: [Note that there is no traditional “Methods” component of this abstract.] Reviews like this are purely critical and don’t necessarily involve performing experiments as in the other abstracts we have seen. Still, a paper like this may incorporate ideas from other sources, much like our traditional definition of experimental research.

Results/findings/product: In a paper like this, the “findings” tend to resemble what you have concluded about something, which will largely be based on your own opinion, supported by various examples. For that reason, the finding of this paper is: “The ‘will of the people,’ actually corresponds to a ‘bounded demos thesis.’” Even though we aren’t sure what the terms mean, we can plainly see that the finding (argument) is in support of “bounded,” rather than “unbounded.”

Conclusion/implications: If our finding is that “bounded” is correct, then what should we conclude? [In this case, the conclusion is simply that the initial author, A.A., is wrong.] Some critical papers attempt to broaden the conclusion to show something outside the scope of the paper. For example, if A.A. believes his “unbounded demos thesis” to be correct (when he is actually mistaken), what does this say about him? About his philosophy? About society as a whole? Maybe people who agree with him are more likely to vote Democrat, more likely to approve of certain immigration policies, more likely to own Labrador retrievers as pets, etc.

Applying These Skills

Now that you know the general layout of an abstract, here are some tips to keep in mind as you write your own:

1. The abstract stands alone

• An abstract shouldn’t be considered “part” of a paper—it should be able to stand independently and still tell the reader something significant.

2. Keep it short

• A general rule of abstract length is 200-300 words, or about 1/10th of the entire paper.

3. Don’t add new information

• If something doesn’t appear in your actual paper, then don’t put it in the abstract.

4. Be consistent with voice, tone, and style

• Try to write the abstract in the same style as your paper (i.e. If you’re not using contractions in your paper, the do not use them in your abstract).

5. Be concise

• Try to shorten your sentences as often as possible. If you can say something clearly in five words rather than ten, then do it.

6. Break up its components

• If allowed, subdivide the components of your abstract with bolded headings for “Background,” “Methods,” etc.

7. The abstract should be part of your writing process

• Consider writing your abstract after you finish your entire paper.
• There’s nothing wrong with copying and pasting important sentences and phrases from your paper … provided that they’re your own words.
• Write multiple drafts, and keep revising. An abstract is very important to your publication (or assignment) and should be treated as such.

"Abstracts." The Writing Center. The University of North Carolina, n.d. Web. 1 Jun 2011. http://www.unc.edu/depts/wcweb/handouts/abstracts.html "Abstracts." The Writing Center. Rensselaer Polytechnic Institute, n.d. Web. 1 Jun 2011. http://www.rpi.edu/web/writingcenter/abstracts.html

Last updated August 2013

• Information For
• Prospective Students
• Current Students
• Faculty and Staff
• Alumni and Friends
• More about LSA
• How Do I Apply?
• LSA Magazine
• Student Resources
• Academic Advising
• Global Studies
• LSA Opportunity Hub
• Social Media
• Update Contact Info
• Privacy Statement
• Report Feedback

Undergraduate Research Center

The following instructions are for the Undergraduate Research Center's Undergraduate Research, Scholarship and Creative Activities Conference, however the general concepts will apply to abstracts for similar conferences.  In the video to the right, Kendon Kurzer, PhD presents guidance from the University Writing Program.  To see abstracts from previous URC Conferences, visit our Abstract Books Page .

What is an abstract?

An abstract is a summary of a research project. Abstracts precede papers in research journals and appear in programs of scholarly conferences. In journals, the abstract allows readers to quickly grasp the purpose and major ideas of a paper and lets other researchers know whether reading the entire paper will be worthwhile. In conferences, the abstract is the advertisement that the paper/presentation deserves the audience's attention.

Why write an abstract?

The abstract allows readers to make decisions about your project. Your sponsoring professor can use the abstract to decide if your research is proceeding smoothly. The conference organizer uses it to decide if your project fits the conference criteria. The conference audience (faculty, administrators, peers, and presenters' families) uses your abstract to decide whether or not to attend your presentation. Your abstract needs to take all these readers into consideration.

How does an abstract appeal to such a broad audience?

The audience for the abstract for the Undergraduate Research, Scholarship and Creative Activities Conference (URSCA) covers the broadest possible scope--from expert to lay person. You need to find a comfortable balance between writing an abstract that both shows your knowledge and yet is still comprehensible--with some effort--by lay members of the audience. Limit the amount of technical language you use and explain it where possible. Always use the full term before you refer to it by acronym Example:  DNA double-stranded breaks (DSBs). Remember that you are yourself an expert in the field that you are writing about--don't take for granted that the reader will share your insider knowledge.

What should the abstract include?

Think of your abstract as a condensed version of your whole project. By reading it, the reader should understand the nature of your research question.

Like abstracts that researchers prepare for scholarly conferences, the abstract you submit for the Undergraduate Research, Scholarship and Creativities Conference (URSCA) will most likely reflect work still in progress at the time you write it. Although the content will vary according to field and specific project, all abstracts, whether in the sciences or the humanities, convey the following information:

• The purpose of the project identifying the area of study to which it belongs.
• The research problem that motivates the project.
• The methods used to address this research problem, documents or evidence analyzed.
• The conclusions reached or, if the research is in progress, what the preliminary results of the investigation suggest, or what the research methods demonstrate.
• The significance of the research project. Why are the results useful? What is new to our understanding as the result of your inquiry?

Whatever kind of research you are doing, your abstract should provide the reader with answers to the following questions: What are you asking? Why is it important? How will you study it? What will you use to demonstrate your conclusions? What are those conclusions? What do they mean?

SUGGESTED CONTENT STRUCTURE:  

Brief Background/Introduction/Research Context:       What do we know about the topic? Why is the topic important?   Present Research Question/Purpose:       What is the study about? Methods/Materials/Subjects/Materials:       How was the study done? Results/Findings:         What was discovered?    Discussion/Conclusion/Implications/Recommendations       What does it mean?

What if the research is in progress and I don't have results yet? 

For the URSCA Conference you can write a "Promissory Abstract"  which will still describe the background, purpose and how you will accomplish your study's purpose and why it is important.  Phrases like  "to show whether"  or "to determine if"  can be helpful to avoid sharing a "hoped for" result. 

Stylistic considerations

The abstract should be one paragraph for the URSCA Conference and should not exceed the word limit (150-200 words). Edit it closely to be sure it meets the Four C's of abstract writing:

• Complete — it covers the major parts of the project.
• Concise — it contains no excess wordiness or unnecessary information.
• Clear — it is readable, well organized, and not too jargon-laden.
• Cohesive — it flows smoothly between the parts.

The importance of understandable language

Because all researchers hope their work will be useful to others, and because good scholarship is increasingly used across disciplines, it is crucial to make the language of your abstracts accessible to a non-specialist. Simplify your language. Friends in another major will spot instantly what needs to be more understandable. Some problem areas to look for:

• Eliminate jargon. Showing off your technical vocabulary will not demonstrate that your research is valuable. If using a technical term is unavoidable, add a non-technical synonym to help a non-specialist infer the term's meaning.
• Omit needless words—redundant modifiers, pompous diction, excessive detail.
• Avoid stringing nouns together (make the relationship clear with prepositions).
• Eliminate "narration," expressions such as "It is my opinion that," "I have concluded," "the main point supporting my view/concerns," or "certainly there is little doubt as to. . . ." Focus attention solely on what the reader needs to know.

Before submitting your abstract to the URSCA Conference:

• Make sure it is within the word limit.  You can start with a large draft and then edit it down to make sure your abstract is complete but also concise.  (Over-writing is all too easy, so reserve time for cutting your abstract down to the essential information.).  
• Make sure the language is understandable by a non-specialist. (Avoid writing for an audience that includes only you and your professor.)
• Have your sponsoring professor work with you and approve the abstract before you submit it online.
• Only one abstract per person is allowed for the URSCA Conference.  

Multimedia Risk Assessment of Biodiesel - Tier II Antfarm Project

Significant knowledge gaps exist in the fate, transport, biodegradation, and toxicity properties of biodiesel when it is leaked into the environment. In order to fill these gaps, a combination of experiments has been developed in a Multimedia Risk Assessment of Biodiesel for the State of California. Currently, in the Tier II experimental phase of this assessment, I am investigating underground plume mobility of 20% and 100% additized and unadditized Soy and Animal Fat based biodiesel blends and comparing them to Ultra Low-Sulfer Diesel #2 (USLD) by filming these fuels as they seep through unsaturated sand, encounter a simulated underground water table, and form a floating lens on top of the water. Thus far, initial findings in analyzing the digital images created during the filming process have indicated that all fuels tested have similar travel times. SoyB20 behaves most like USLD in that they both have a similar lateral dispersion lens on top of the water table. In contrast, Animal Fat B100 appears to be most different from ULSD in that it has a narrower residual plume in the unsaturated sand, as well as a narrower and deeper lens formation on top of the water table.

Narrative Representation of Grief

In William Faulkner's As I Lay Dying and Kazuo Ishiguro's Never Let Me Go how can grief, an incomprehensible and incommunicable emotion, be represented in fiction? Is it paradoxical, or futile, to do so? I look at two novels that struggle with representing intense combinations of individual and communal grief: William Faulkner's As I Lay Dying and Kazuo Ishiguro's Never Let Me Go . At first glance, the novels appear to have nothing in common: Faulkner's is a notoriously bleak odyssey told in emotionally heavy stream-of-consciousness narrative, while Ishiguro's is a near-kitschy blend of a coming-of-age tale and a sci-fi dystopia. But they share a rare common thread. They do not try to convey a story, a character, an argument, or a realization, so much as they try to convey an emotion. The novels' common struggle is visible through their formal elements, down to the most basic technical aspects of how the stories are told. Each text, in its own way, enacts the trauma felt by its characters because of their grief, and also the frustration felt by its narrator (or narrators) because of the complex and guilty task of witnessing for grief and loss.

This webpage was based on articles written by Professor Diana Strazdes, Art History and Dr. Amy Clarke, University Writing Program, UC Davis. Thanks to both for their contributions.

Role of an Abstract in Research Paper With Examples

Why does one write an abstract? What is so intriguing about writing an abstract in research paper after writing a full length research paper? How do research paper abstracts or summaries help a researcher during research publishing? These are the most common and frequently pondered upon questions that early career researchers search answers for over the internet!

Table of Contents

What does Abstract mean in Research?

In Research, abstract is “a well-developed single paragraph which is approximately 250 words in length”. Furthermore, it is single-spaced single spaced. Abstract outlines all the parts of the paper briefly. Although the abstract is placed in the beginning of the research paper immediately after research title , the abstract is the last thing a researcher writes.

Why Is an Abstract Necessary in Research Paper?

Abstract is a concise academic text that –

• Helps the potential reader get the relevance of your research study for their own research
• Communicates your key findings for those who have time constraints in reading your paper
• And helps rank the article on search engines based on the keywords on academic databases.

Purpose of Writing an Abstract in Research

Abstracts are required for –

• Submission of articles to journals
• Application for research grants
• Completion and submission of thesis
• Submission of proposals for conference papers.

Aspects Included in an Abstract

The format of your abstract depends on the field of research, in which you are working. However, all abstracts broadly cover the following sections:

Reason for Writing

One can start with the importance of conducting their research study. Furthermore, you could start with a broader research question and address why would the reader be interested in that particular research question.

Research Problem

You could mention what problem the research study chooses to address. Moreover, you could elaborate about the scope of the project, the main argument, brief about thesis objective or what the study claims.

• Methodology

Furthermore, you could mention a line or two about what approach and specific models the research study uses in the scientific work. Some research studies may discuss the evidences in throughout the paper, so instead of writing about methodologies you could mention the types of evidence used in the research.

The scientific research aims to get the specific data that indicates the results of the project. Therefore, you could mention the results and discuss the findings in a broader and general way.

Finally, you could discuss how the research work contributes to the scientific society and adds knowledge on the topic. Also, you could specify if your findings or inferences could help future research and researchers.

Types of Abstracts

Based on the abstract content —, 1. descriptive.

This abstract in research paper is usually short (50-100 words). These abstracts have common sections, such as –

• Focus of research
• Overview of the study.

This type of research does not include detailed presentation of results and only mention results through a phrase without contributing numerical or statistical data . Descriptive abstracts guide readers on the nature of contents of the article.

2. Informative

This abstract gives the essence of what the report is about and it is usually about 200 words. These abstracts have common sections, such as –

• Aim or purpose

This abstract provides an accurate data on the contents of the work, especially on the results section.

Based on the writing format —

1. structured.

This type of abstract has a paragraph for each section: Introduction, Materials and Methods, Results, and Conclusion. Also, structured abstracts are often required for informative abstracts.

2. Semi-structured

A semi-structured abstract is written in only one paragraph, wherein each sentence corresponds to a section. Furthermore, all the sections mentioned in the structured abstract are present in the semi-structured abstract.

3. Non-structured

In a non-structured abstract there are no divisions between each section. The sentences are included in a single paragraph. This type of presentation is ideal for descriptive abstracts.

Examples of Abstracts

Abstract example 1: clinical research.

Neutralization of Omicron BA.1, BA.2, and BA.3 SARS-CoV-2 by 3 doses of BNT162b2 vaccine

Abstract: The newly emerged Omicron SARS-CoV-2 has several distinct sublineages including BA.1, BA.2, and BA.3. BA.1 accounts for the initial surge and is being replaced by BA.2, whereas BA.3 is at a low prevalence at this time. Here we report the neutralization of BNT162b2-vaccinated sera (collected 1 month after dose 3) against the three Omicron sublineages. To facilitate the neutralization testing, we have engineered the complete BA.1, BA.2, or BA.3 spike into an mNeonGreen USA-WA1/2020 SARS-CoV-2. All BNT162b2-vaccinated sera neutralize USA-WA1/2020, BA.1-, BA.2-, and BA.3-spike SARS-CoV-2s with titers of >20; the neutralization geometric mean titers (GMTs) against the four viruses are 1211, 336, 300, and 190, respectively. Thus, the BA.1-, BA.2-, and BA.3-spike SARS-CoV-2s are 3.6-, 4.0-, and 6.4-fold less efficiently neutralized than the USA-WA1/2020, respectively. Our data have implications in vaccine strategy and understanding the biology of Omicron sublineages.

Type of Abstract: Informative and non-structured

Abstract Example 2: Material Science and Chemistry

Breaking the nanoparticle’s dispersible limit via rotatable surface ligands

Abstract: Achieving versatile dispersion of nanoparticles in a broad range of solvents (e.g., water, oil, and biofluids) without repeatedly recourse to chemical modifications are desirable in optoelectronic devices, self-assembly, sensing, and biomedical fields. However, such a target is limited by the strategies used to decorate nanoparticle’s surface properties, leading to a narrow range of solvents for existing nanoparticles. Here we report a concept to break the nanoparticle’s dispersible limit via electrochemically anchoring surface ligands capable of sensing the surrounding liquid medium and rotating to adapt to it, immediately forming stable dispersions in a wide range of solvents (polar and nonpolar, biofluids, etc.). Moreover, the smart nanoparticles can be continuously electrodeposited in the electrolyte, overcoming the electrode surface-confined low throughput limitation of conventional electrodeposition methods. The anomalous dispersive property of the smart Ag nanoparticles enables them to resist bacteria secreted species-induced aggregation and the structural similarity of the surface ligands to that of the bacterial membrane assists them to enter the bacteria, leading to high antibacterial activity. The simple but massive fabrication process and the enhanced dispersion properties offer great application opportunities to the smart nanoparticles in diverse fields.

Type of Abstract: Descriptive and non-structured

Abstract Example 3: Clinical Toxicology

Evaluation of dexmedetomidine therapy for sedation in patients with toxicological events at an academic medical center

Introduction: Although clinical use of dexmedetomidine (DEX), an alpha2-adrenergic receptor agonist, has increased, its role in patients admitted to intensive care units secondary to toxicological sequelae has not been well established.

Objectives: The primary objective of this study was to describe clinical and adverse effects observed in poisoned patients receiving DEX for sedation.

Methods: This was an observational case series with retrospective chart review of poisoned patients who received DEX for sedation at an academic medical center. The primary endpoint was incidence of adverse effects of DEX therapy including bradycardia, hypotension, seizures, and arrhythmias. For comparison, vital signs were collected hourly for the 5 h preceding the DEX therapy and every hour during DEX therapy until the therapy ended. Additional endpoints included therapy duration; time within target Richmond Agitation Sedation Score (RASS); and concomitant sedation, analgesia, and vasopressor requirements.

Results: Twenty-two patients were included. Median initial and median DEX infusion rates were similar to the commonly used rates for sedation. Median heart rate was lower during the therapy (82 vs. 93 beats/minute, p < 0.05). Median systolic blood pressure before and during therapy was similar (111 vs. 109 mmHg, p = 0.745). Five patients experienced an adverse effect per study definitions during therapy. No additional adverse effects were noted. Median time within target RASS and duration of therapy was 6.5 and 44.5 h, respectively. Seventeen patients (77%) had concomitant use of other sedation and/or analgesia with four (23%) of these patients requiring additional agents after DEX initiation. Seven patients (32%) had concomitant vasopressor support with four (57%) of these patients requiring vasopressor support after DEX initiation.

Conclusion: Common adverse effects of DEX were noted in this study. The requirement for vasopressor support during therapy warrants further investigation into the safety of DEX in poisoned patients. Larger, comparative studies need to be performed before the use of DEX can be routinely recommended in poisoned patients.

Keywords: Adverse effects; Alpha2-adrenergic receptor agonist; Overdose; Safety.

Type of Abstract: Informative and structured .

How was your experience  writing an abstract? What type of abstracts have you written? Do write to us or leave a comment below.

Rate this article Cancel Reply

Your email address will not be published.

Enago Academy's Most Popular Articles

• AI in Academia
• Trending Now

Simplifying the Literature Review Journey — A comparative analysis of 6 AI summarization tools

Imagine having to skim through and read mountains of research papers and books, only to…

• Reporting Research

Choosing the Right Analytical Approach: Thematic analysis vs. content analysis for data interpretation

In research, choosing the right approach to understand data is crucial for deriving meaningful insights.…

Comparing Cross Sectional and Longitudinal Studies: 5 steps for choosing the right approach

The process of choosing the right research design can put ourselves at the crossroads of…

• Career Corner

Unlocking the Power of Networking in Academic Conferences

Embarking on your first academic conference experience? Fear not, we got you covered! Academic conferences…

Research Recommendations – Guiding policy-makers for evidence-based decision making

Research recommendations play a crucial role in guiding scholars and researchers toward fruitful avenues of…

Choosing the Right Analytical Approach: Thematic analysis vs. content analysis for…

Comparing Cross Sectional and Longitudinal Studies: 5 steps for choosing the right…

8 Effective Strategies to Write Argumentative Essays

Sign-up to read more

Subscribe for free to get unrestricted access to all our resources on research writing and academic publishing including:

• 2000+ blog articles
• 50+ Webinars
• 10+ Expert podcasts
• 50+ Infographics
• 10+ Checklists
• Research Guides

We hate spam too. We promise to protect your privacy and never spam you.

I am looking for Editing/ Proofreading services for my manuscript Tentative date of next journal submission:

As a researcher, what do you consider most when choosing an image manipulation detector?

Get science-backed answers as you write with Paperpal's Research feature

What is Research Methodology? Definition, Types, and Examples

Research methodology 1,2 is a structured and scientific approach used to collect, analyze, and interpret quantitative or qualitative data to answer research questions or test hypotheses. A research methodology is like a plan for carrying out research and helps keep researchers on track by limiting the scope of the research. Several aspects must be considered before selecting an appropriate research methodology, such as research limitations and ethical concerns that may affect your research.

The research methodology section in a scientific paper describes the different methodological choices made, such as the data collection and analysis methods, and why these choices were selected. The reasons should explain why the methods chosen are the most appropriate to answer the research question. A good research methodology also helps ensure the reliability and validity of the research findings. There are three types of research methodology—quantitative, qualitative, and mixed-method, which can be chosen based on the research objectives.

What is research methodology ?

A research methodology describes the techniques and procedures used to identify and analyze information regarding a specific research topic. It is a process by which researchers design their study so that they can achieve their objectives using the selected research instruments. It includes all the important aspects of research, including research design, data collection methods, data analysis methods, and the overall framework within which the research is conducted. While these points can help you understand what is research methodology, you also need to know why it is important to pick the right methodology.

Why is research methodology important?

Having a good research methodology in place has the following advantages: 3

• Helps other researchers who may want to replicate your research; the explanations will be of benefit to them.
• You can easily answer any questions about your research if they arise at a later stage.
• A research methodology provides a framework and guidelines for researchers to clearly define research questions, hypotheses, and objectives.
• It helps researchers identify the most appropriate research design, sampling technique, and data collection and analysis methods.
• A sound research methodology helps researchers ensure that their findings are valid and reliable and free from biases and errors.
• It also helps ensure that ethical guidelines are followed while conducting research.
• A good research methodology helps researchers in planning their research efficiently, by ensuring optimum usage of their time and resources.

Writing the methods section of a research paper? Let Paperpal help you achieve perfection

Types of research methodology.

There are three types of research methodology based on the type of research and the data required. 1

• Quantitative research methodology focuses on measuring and testing numerical data. This approach is good for reaching a large number of people in a short amount of time. This type of research helps in testing the causal relationships between variables, making predictions, and generalizing results to wider populations.
• Qualitative research methodology examines the opinions, behaviors, and experiences of people. It collects and analyzes words and textual data. This research methodology requires fewer participants but is still more time consuming because the time spent per participant is quite large. This method is used in exploratory research where the research problem being investigated is not clearly defined.
• Mixed-method research methodology uses the characteristics of both quantitative and qualitative research methodologies in the same study. This method allows researchers to validate their findings, verify if the results observed using both methods are complementary, and explain any unexpected results obtained from one method by using the other method.

What are the types of sampling designs in research methodology?

Sampling 4 is an important part of a research methodology and involves selecting a representative sample of the population to conduct the study, making statistical inferences about them, and estimating the characteristics of the whole population based on these inferences. There are two types of sampling designs in research methodology—probability and nonprobability.

• Probability sampling

In this type of sampling design, a sample is chosen from a larger population using some form of random selection, that is, every member of the population has an equal chance of being selected. The different types of probability sampling are:

• Systematic —sample members are chosen at regular intervals. It requires selecting a starting point for the sample and sample size determination that can be repeated at regular intervals. This type of sampling method has a predefined range; hence, it is the least time consuming.
• Stratified —researchers divide the population into smaller groups that don’t overlap but represent the entire population. While sampling, these groups can be organized, and then a sample can be drawn from each group separately.
• Cluster —the population is divided into clusters based on demographic parameters like age, sex, location, etc.
• Convenience —selects participants who are most easily accessible to researchers due to geographical proximity, availability at a particular time, etc.
• Purposive —participants are selected at the researcher’s discretion. Researchers consider the purpose of the study and the understanding of the target audience.
• Snowball —already selected participants use their social networks to refer the researcher to other potential participants.
• Quota —while designing the study, the researchers decide how many people with which characteristics to include as participants. The characteristics help in choosing people most likely to provide insights into the subject.

What are data collection methods?

During research, data are collected using various methods depending on the research methodology being followed and the research methods being undertaken. Both qualitative and quantitative research have different data collection methods, as listed below.

Qualitative research 5

• One-on-one interviews: Helps the interviewers understand a respondent’s subjective opinion and experience pertaining to a specific topic or event
• Document study/literature review/record keeping: Researchers’ review of already existing written materials such as archives, annual reports, research articles, guidelines, policy documents, etc.
• Focus groups: Constructive discussions that usually include a small sample of about 6-10 people and a moderator, to understand the participants’ opinion on a given topic.
• Qualitative observation : Researchers collect data using their five senses (sight, smell, touch, taste, and hearing).

Quantitative research 6

• Sampling: The most common type is probability sampling.
• Interviews: Commonly telephonic or done in-person.
• Observations: Structured observations are most commonly used in quantitative research. In this method, researchers make observations about specific behaviors of individuals in a structured setting.
• Document review: Reviewing existing research or documents to collect evidence for supporting the research.
• Surveys and questionnaires. Surveys can be administered both online and offline depending on the requirement and sample size.

Let Paperpal help you write the perfect research methods section. Start now!

What are data analysis methods.

The data collected using the various methods for qualitative and quantitative research need to be analyzed to generate meaningful conclusions. These data analysis methods 7 also differ between quantitative and qualitative research.

Quantitative research involves a deductive method for data analysis where hypotheses are developed at the beginning of the research and precise measurement is required. The methods include statistical analysis applications to analyze numerical data and are grouped into two categories—descriptive and inferential.

Descriptive analysis is used to describe the basic features of different types of data to present it in a way that ensures the patterns become meaningful. The different types of descriptive analysis methods are:

• Measures of frequency (count, percent, frequency)
• Measures of central tendency (mean, median, mode)
• Measures of dispersion or variation (range, variance, standard deviation)
• Measure of position (percentile ranks, quartile ranks)

Inferential analysis is used to make predictions about a larger population based on the analysis of the data collected from a smaller population. This analysis is used to study the relationships between different variables. Some commonly used inferential data analysis methods are:

• Correlation: To understand the relationship between two or more variables.
• Cross-tabulation: Analyze the relationship between multiple variables.
• Regression analysis: Study the impact of independent variables on the dependent variable.
• Frequency tables: To understand the frequency of data.
• Analysis of variance: To test the degree to which two or more variables differ in an experiment.

Qualitative research involves an inductive method for data analysis where hypotheses are developed after data collection. The methods include:

• Content analysis: For analyzing documented information from text and images by determining the presence of certain words or concepts in texts.
• Narrative analysis: For analyzing content obtained from sources such as interviews, field observations, and surveys. The stories and opinions shared by people are used to answer research questions.
• Discourse analysis: For analyzing interactions with people considering the social context, that is, the lifestyle and environment, under which the interaction occurs.
• Grounded theory: Involves hypothesis creation by data collection and analysis to explain why a phenomenon occurred.
• Thematic analysis: To identify important themes or patterns in data and use these to address an issue.

How to choose a research methodology?

Here are some important factors to consider when choosing a research methodology: 8

• Research objectives, aims, and questions —these would help structure the research design.
• Review existing literature to identify any gaps in knowledge.
• Check the statistical requirements —if data-driven or statistical results are needed then quantitative research is the best. If the research questions can be answered based on people’s opinions and perceptions, then qualitative research is most suitable.
• Sample size —sample size can often determine the feasibility of a research methodology. For a large sample, less effort- and time-intensive methods are appropriate.
• Constraints —constraints of time, geography, and resources can help define the appropriate methodology.

Got writer’s block? Kickstart your research paper writing with Paperpal now!

How to write a research methodology .

A research methodology should include the following components: 3,9

• Research design —should be selected based on the research question and the data required. Common research designs include experimental, quasi-experimental, correlational, descriptive, and exploratory.
• Research method —this can be quantitative, qualitative, or mixed-method.
• Reason for selecting a specific methodology —explain why this methodology is the most suitable to answer your research problem.
• Research instruments —explain the research instruments you plan to use, mainly referring to the data collection methods such as interviews, surveys, etc. Here as well, a reason should be mentioned for selecting the particular instrument.
• Sampling —this involves selecting a representative subset of the population being studied.
• Data collection —involves gathering data using several data collection methods, such as surveys, interviews, etc.
• Data analysis —describe the data analysis methods you will use once you’ve collected the data.
• Research limitations —mention any limitations you foresee while conducting your research.
• Validity and reliability —validity helps identify the accuracy and truthfulness of the findings; reliability refers to the consistency and stability of the results over time and across different conditions.
• Ethical considerations —research should be conducted ethically. The considerations include obtaining consent from participants, maintaining confidentiality, and addressing conflicts of interest.

Streamline Your Research Paper Writing Process with Paperpal

The methods section is a critical part of the research papers, allowing researchers to use this to understand your findings and replicate your work when pursuing their own research. However, it is usually also the most difficult section to write. This is where Paperpal can help you overcome the writer’s block and create the first draft in minutes with Paperpal Copilot, its secure generative AI feature suite.  

With Paperpal you can get research advice, write and refine your work, rephrase and verify the writing, and ensure submission readiness, all in one place. Here’s how you can use Paperpal to develop the first draft of your methods section.  

• Generate an outline: Input some details about your research to instantly generate an outline for your methods section 
• Develop the section: Use the outline and suggested sentence templates to expand your ideas and develop the first draft.  
• P araph ras e and trim : Get clear, concise academic text with paraphrasing that conveys your work effectively and word reduction to fix redundancies. 
• Choose the right words: Enhance text by choosing contextual synonyms based on how the words have been used in previously published work.  
• Check and verify text : Make sure the generated text showcases your methods correctly, has all the right citations, and is original and authentic. .   

You can repeat this process to develop each section of your research manuscript, including the title, abstract and keywords. Ready to write your research papers faster, better, and without the stress? Sign up for Paperpal and start writing today!

Frequently Asked Questions

Q1. What are the key components of research methodology?

A1. A good research methodology has the following key components:

• Research design
• Data collection procedures
• Data analysis methods
• Ethical considerations

Q2. Why is ethical consideration important in research methodology?

A2. Ethical consideration is important in research methodology to ensure the readers of the reliability and validity of the study. Researchers must clearly mention the ethical norms and standards followed during the conduct of the research and also mention if the research has been cleared by any institutional board. The following 10 points are the important principles related to ethical considerations: 10

• Participants should not be subjected to harm.
• Respect for the dignity of participants should be prioritized.
• Full consent should be obtained from participants before the study.
• Participants’ privacy should be ensured.
• Confidentiality of the research data should be ensured.
• Anonymity of individuals and organizations participating in the research should be maintained.
• The aims and objectives of the research should not be exaggerated.
• Affiliations, sources of funding, and any possible conflicts of interest should be declared.
• Communication in relation to the research should be honest and transparent.
• Misleading information and biased representation of primary data findings should be avoided.

Q3. What is the difference between methodology and method?

A3. Research methodology is different from a research method, although both terms are often confused. Research methods are the tools used to gather data, while the research methodology provides a framework for how research is planned, conducted, and analyzed. The latter guides researchers in making decisions about the most appropriate methods for their research. Research methods refer to the specific techniques, procedures, and tools used by researchers to collect, analyze, and interpret data, for instance surveys, questionnaires, interviews, etc.

Research methodology is, thus, an integral part of a research study. It helps ensure that you stay on track to meet your research objectives and answer your research questions using the most appropriate data collection and analysis tools based on your research design.

Accelerate your research paper writing with Paperpal. Try for free now!

• Research methodologies. Pfeiffer Library website. Accessed August 15, 2023. https://library.tiffin.edu/researchmethodologies/whatareresearchmethodologies
• Types of research methodology. Eduvoice website. Accessed August 16, 2023. https://eduvoice.in/types-research-methodology/
• The basics of research methodology: A key to quality research. Voxco. Accessed August 16, 2023. https://www.voxco.com/blog/what-is-research-methodology/
• Sampling methods: Types with examples. QuestionPro website. Accessed August 16, 2023. https://www.questionpro.com/blog/types-of-sampling-for-social-research/
• What is qualitative research? Methods, types, approaches, examples. Researcher.Life blog. Accessed August 15, 2023. https://researcher.life/blog/article/what-is-qualitative-research-methods-types-examples/
• What is quantitative research? Definition, methods, types, and examples. Researcher.Life blog. Accessed August 15, 2023. https://researcher.life/blog/article/what-is-quantitative-research-types-and-examples/
• Data analysis in research: Types & methods. QuestionPro website. Accessed August 16, 2023. https://www.questionpro.com/blog/data-analysis-in-research/#Data_analysis_in_qualitative_research
• Factors to consider while choosing the right research methodology. PhD Monster website. Accessed August 17, 2023. https://www.phdmonster.com/factors-to-consider-while-choosing-the-right-research-methodology/
• What is research methodology? Research and writing guides. Accessed August 14, 2023. https://paperpile.com/g/what-is-research-methodology/
• Ethical considerations. Business research methodology website. Accessed August 17, 2023. https://research-methodology.net/research-methodology/ethical-considerations/

Paperpal is a comprehensive AI writing toolkit that helps students and researchers achieve 2x the writing in half the time. It leverages 21+ years of STM experience and insights from millions of research articles to provide in-depth academic writing, language editing, and submission readiness support to help you write better, faster.  

Get accurate academic translations, rewriting support, grammar checks, vocabulary suggestions, and generative AI assistance that delivers human precision at machine speed. Try for free or upgrade to Paperpal Prime starting at US$19 a month to access premium features, including consistency, plagiarism, and 30+ submission readiness checks to help you succeed.  

Experience the future of academic writing – Sign up to Paperpal and start writing for free!  

Related Reads:

• Dangling Modifiers and How to Avoid Them in Your Writing 
• Webinar: How to Use Generative AI Tools Ethically in Your Academic Writing
• Research Outlines: How to Write An Introduction Section in Minutes with Paperpal Copilot
• How to Paraphrase Research Papers Effectively

Language and Grammar Rules for Academic Writing

Climatic vs. climactic: difference and examples, you may also like, how to write a high-quality conference paper, how paperpal is enhancing academic productivity and accelerating..., academic editing: how to self-edit academic text with..., 4 ways paperpal encourages responsible writing with ai, what are scholarly sources and where can you..., how to write a hypothesis types and examples , what is academic writing: tips for students, what is hedging in academic writing  , how to use ai to enhance your college..., how to use paperpal to generate emails &....

• Privacy Policy

Home » Research Methodology – Types, Examples and writing Guide

Research Methodology – Types, Examples and writing Guide

Table of Contents

Research Methodology

Definition:

Research Methodology refers to the systematic and scientific approach used to conduct research, investigate problems, and gather data and information for a specific purpose. It involves the techniques and procedures used to identify, collect , analyze , and interpret data to answer research questions or solve research problems . Moreover, They are philosophical and theoretical frameworks that guide the research process.

Structure of Research Methodology

Research methodology formats can vary depending on the specific requirements of the research project, but the following is a basic example of a structure for a research methodology section:

I. Introduction

• Provide an overview of the research problem and the need for a research methodology section
• Outline the main research questions and objectives

II. Research Design

• Explain the research design chosen and why it is appropriate for the research question(s) and objectives
• Discuss any alternative research designs considered and why they were not chosen
• Describe the research setting and participants (if applicable)

III. Data Collection Methods

• Describe the methods used to collect data (e.g., surveys, interviews, observations)
• Explain how the data collection methods were chosen and why they are appropriate for the research question(s) and objectives
• Detail any procedures or instruments used for data collection

IV. Data Analysis Methods

• Describe the methods used to analyze the data (e.g., statistical analysis, content analysis )
• Explain how the data analysis methods were chosen and why they are appropriate for the research question(s) and objectives
• Detail any procedures or software used for data analysis

V. Ethical Considerations

• Discuss any ethical issues that may arise from the research and how they were addressed
• Explain how informed consent was obtained (if applicable)
• Detail any measures taken to ensure confidentiality and anonymity

VI. Limitations

• Identify any potential limitations of the research methodology and how they may impact the results and conclusions

VII. Conclusion

• Summarize the key aspects of the research methodology section
• Explain how the research methodology addresses the research question(s) and objectives

Research Methodology Types

Types of Research Methodology are as follows:

Quantitative Research Methodology

This is a research methodology that involves the collection and analysis of numerical data using statistical methods. This type of research is often used to study cause-and-effect relationships and to make predictions.

Qualitative Research Methodology

This is a research methodology that involves the collection and analysis of non-numerical data such as words, images, and observations. This type of research is often used to explore complex phenomena, to gain an in-depth understanding of a particular topic, and to generate hypotheses.

Mixed-Methods Research Methodology

This is a research methodology that combines elements of both quantitative and qualitative research. This approach can be particularly useful for studies that aim to explore complex phenomena and to provide a more comprehensive understanding of a particular topic.

Case Study Research Methodology

This is a research methodology that involves in-depth examination of a single case or a small number of cases. Case studies are often used in psychology, sociology, and anthropology to gain a detailed understanding of a particular individual or group.

Action Research Methodology

This is a research methodology that involves a collaborative process between researchers and practitioners to identify and solve real-world problems. Action research is often used in education, healthcare, and social work.

Experimental Research Methodology

This is a research methodology that involves the manipulation of one or more independent variables to observe their effects on a dependent variable. Experimental research is often used to study cause-and-effect relationships and to make predictions.

Survey Research Methodology

This is a research methodology that involves the collection of data from a sample of individuals using questionnaires or interviews. Survey research is often used to study attitudes, opinions, and behaviors.

Grounded Theory Research Methodology

This is a research methodology that involves the development of theories based on the data collected during the research process. Grounded theory is often used in sociology and anthropology to generate theories about social phenomena.

Research Methodology Example

An Example of Research Methodology could be the following:

Research Methodology for Investigating the Effectiveness of Cognitive Behavioral Therapy in Reducing Symptoms of Depression in Adults

Introduction:

The aim of this research is to investigate the effectiveness of cognitive-behavioral therapy (CBT) in reducing symptoms of depression in adults. To achieve this objective, a randomized controlled trial (RCT) will be conducted using a mixed-methods approach.

Research Design:

The study will follow a pre-test and post-test design with two groups: an experimental group receiving CBT and a control group receiving no intervention. The study will also include a qualitative component, in which semi-structured interviews will be conducted with a subset of participants to explore their experiences of receiving CBT.

Participants:

Participants will be recruited from community mental health clinics in the local area. The sample will consist of 100 adults aged 18-65 years old who meet the diagnostic criteria for major depressive disorder. Participants will be randomly assigned to either the experimental group or the control group.

Intervention :

The experimental group will receive 12 weekly sessions of CBT, each lasting 60 minutes. The intervention will be delivered by licensed mental health professionals who have been trained in CBT. The control group will receive no intervention during the study period.

Data Collection:

Quantitative data will be collected through the use of standardized measures such as the Beck Depression Inventory-II (BDI-II) and the Generalized Anxiety Disorder-7 (GAD-7). Data will be collected at baseline, immediately after the intervention, and at a 3-month follow-up. Qualitative data will be collected through semi-structured interviews with a subset of participants from the experimental group. The interviews will be conducted at the end of the intervention period, and will explore participants’ experiences of receiving CBT.

Data Analysis:

Quantitative data will be analyzed using descriptive statistics, t-tests, and mixed-model analyses of variance (ANOVA) to assess the effectiveness of the intervention. Qualitative data will be analyzed using thematic analysis to identify common themes and patterns in participants’ experiences of receiving CBT.

Ethical Considerations:

This study will comply with ethical guidelines for research involving human subjects. Participants will provide informed consent before participating in the study, and their privacy and confidentiality will be protected throughout the study. Any adverse events or reactions will be reported and managed appropriately.

Data Management:

All data collected will be kept confidential and stored securely using password-protected databases. Identifying information will be removed from qualitative data transcripts to ensure participants’ anonymity.

Limitations:

One potential limitation of this study is that it only focuses on one type of psychotherapy, CBT, and may not generalize to other types of therapy or interventions. Another limitation is that the study will only include participants from community mental health clinics, which may not be representative of the general population.

Conclusion:

This research aims to investigate the effectiveness of CBT in reducing symptoms of depression in adults. By using a randomized controlled trial and a mixed-methods approach, the study will provide valuable insights into the mechanisms underlying the relationship between CBT and depression. The results of this study will have important implications for the development of effective treatments for depression in clinical settings.

How to Write Research Methodology

Writing a research methodology involves explaining the methods and techniques you used to conduct research, collect data, and analyze results. It’s an essential section of any research paper or thesis, as it helps readers understand the validity and reliability of your findings. Here are the steps to write a research methodology:

• Start by explaining your research question: Begin the methodology section by restating your research question and explaining why it’s important. This helps readers understand the purpose of your research and the rationale behind your methods.
• Describe your research design: Explain the overall approach you used to conduct research. This could be a qualitative or quantitative research design, experimental or non-experimental, case study or survey, etc. Discuss the advantages and limitations of the chosen design.
• Discuss your sample: Describe the participants or subjects you included in your study. Include details such as their demographics, sampling method, sample size, and any exclusion criteria used.
• Describe your data collection methods : Explain how you collected data from your participants. This could include surveys, interviews, observations, questionnaires, or experiments. Include details on how you obtained informed consent, how you administered the tools, and how you minimized the risk of bias.
• Explain your data analysis techniques: Describe the methods you used to analyze the data you collected. This could include statistical analysis, content analysis, thematic analysis, or discourse analysis. Explain how you dealt with missing data, outliers, and any other issues that arose during the analysis.
• Discuss the validity and reliability of your research : Explain how you ensured the validity and reliability of your study. This could include measures such as triangulation, member checking, peer review, or inter-coder reliability.
• Acknowledge any limitations of your research: Discuss any limitations of your study, including any potential threats to validity or generalizability. This helps readers understand the scope of your findings and how they might apply to other contexts.
• Provide a summary: End the methodology section by summarizing the methods and techniques you used to conduct your research. This provides a clear overview of your research methodology and helps readers understand the process you followed to arrive at your findings.

When to Write Research Methodology

Research methodology is typically written after the research proposal has been approved and before the actual research is conducted. It should be written prior to data collection and analysis, as it provides a clear roadmap for the research project.

The research methodology is an important section of any research paper or thesis, as it describes the methods and procedures that will be used to conduct the research. It should include details about the research design, data collection methods, data analysis techniques, and any ethical considerations.

The methodology should be written in a clear and concise manner, and it should be based on established research practices and standards. It is important to provide enough detail so that the reader can understand how the research was conducted and evaluate the validity of the results.

Applications of Research Methodology

Here are some of the applications of research methodology:

• To identify the research problem: Research methodology is used to identify the research problem, which is the first step in conducting any research.
• To design the research: Research methodology helps in designing the research by selecting the appropriate research method, research design, and sampling technique.
• To collect data: Research methodology provides a systematic approach to collect data from primary and secondary sources.
• To analyze data: Research methodology helps in analyzing the collected data using various statistical and non-statistical techniques.
• To test hypotheses: Research methodology provides a framework for testing hypotheses and drawing conclusions based on the analysis of data.
• To generalize findings: Research methodology helps in generalizing the findings of the research to the target population.
• To develop theories : Research methodology is used to develop new theories and modify existing theories based on the findings of the research.
• To evaluate programs and policies : Research methodology is used to evaluate the effectiveness of programs and policies by collecting data and analyzing it.
• To improve decision-making: Research methodology helps in making informed decisions by providing reliable and valid data.

Purpose of Research Methodology

Research methodology serves several important purposes, including:

• To guide the research process: Research methodology provides a systematic framework for conducting research. It helps researchers to plan their research, define their research questions, and select appropriate methods and techniques for collecting and analyzing data.
• To ensure research quality: Research methodology helps researchers to ensure that their research is rigorous, reliable, and valid. It provides guidelines for minimizing bias and error in data collection and analysis, and for ensuring that research findings are accurate and trustworthy.
• To replicate research: Research methodology provides a clear and detailed account of the research process, making it possible for other researchers to replicate the study and verify its findings.
• To advance knowledge: Research methodology enables researchers to generate new knowledge and to contribute to the body of knowledge in their field. It provides a means for testing hypotheses, exploring new ideas, and discovering new insights.
• To inform decision-making: Research methodology provides evidence-based information that can inform policy and decision-making in a variety of fields, including medicine, public health, education, and business.

Advantages of Research Methodology

Research methodology has several advantages that make it a valuable tool for conducting research in various fields. Here are some of the key advantages of research methodology:

• Systematic and structured approach : Research methodology provides a systematic and structured approach to conducting research, which ensures that the research is conducted in a rigorous and comprehensive manner.
• Objectivity : Research methodology aims to ensure objectivity in the research process, which means that the research findings are based on evidence and not influenced by personal bias or subjective opinions.
• Replicability : Research methodology ensures that research can be replicated by other researchers, which is essential for validating research findings and ensuring their accuracy.
• Reliability : Research methodology aims to ensure that the research findings are reliable, which means that they are consistent and can be depended upon.
• Validity : Research methodology ensures that the research findings are valid, which means that they accurately reflect the research question or hypothesis being tested.
• Efficiency : Research methodology provides a structured and efficient way of conducting research, which helps to save time and resources.
• Flexibility : Research methodology allows researchers to choose the most appropriate research methods and techniques based on the research question, data availability, and other relevant factors.
• Scope for innovation: Research methodology provides scope for innovation and creativity in designing research studies and developing new research techniques.

Research Methodology Vs Research Methods

About the author.

Muhammad Hassan

Researcher, Academic Writer, Web developer

You may also like

How to Cite Research Paper – All Formats and...

Data Collection – Methods Types and Examples

Delimitations in Research – Types, Examples and...

Research Paper Format – Types, Examples and...

Research Process – Steps, Examples and Tips

Research Design – Types, Methods and Examples

• Open access
• Published: 07 September 2020

A tutorial on methodological studies: the what, when, how and why

• Lawrence Mbuagbaw   ORCID: orcid.org/0000-0001-5855-5461 1 , 2 , 3 ,
• Daeria O. Lawson 1 ,
• Livia Puljak 4 ,
• David B. Allison 5 &
• Lehana Thabane 1 , 2 , 6 , 7 , 8  

BMC Medical Research Methodology volume  20 , Article number:  226 ( 2020 ) Cite this article

39k Accesses

53 Citations

58 Altmetric

Metrics details

Methodological studies – studies that evaluate the design, analysis or reporting of other research-related reports – play an important role in health research. They help to highlight issues in the conduct of research with the aim of improving health research methodology, and ultimately reducing research waste.

We provide an overview of some of the key aspects of methodological studies such as what they are, and when, how and why they are done. We adopt a “frequently asked questions” format to facilitate reading this paper and provide multiple examples to help guide researchers interested in conducting methodological studies. Some of the topics addressed include: is it necessary to publish a study protocol? How to select relevant research reports and databases for a methodological study? What approaches to data extraction and statistical analysis should be considered when conducting a methodological study? What are potential threats to validity and is there a way to appraise the quality of methodological studies?

Appropriate reflection and application of basic principles of epidemiology and biostatistics are required in the design and analysis of methodological studies. This paper provides an introduction for further discussion about the conduct of methodological studies.

Peer Review reports

The field of meta-research (or research-on-research) has proliferated in recent years in response to issues with research quality and conduct [ 1 , 2 , 3 ]. As the name suggests, this field targets issues with research design, conduct, analysis and reporting. Various types of research reports are often examined as the unit of analysis in these studies (e.g. abstracts, full manuscripts, trial registry entries). Like many other novel fields of research, meta-research has seen a proliferation of use before the development of reporting guidance. For example, this was the case with randomized trials for which risk of bias tools and reporting guidelines were only developed much later – after many trials had been published and noted to have limitations [ 4 , 5 ]; and for systematic reviews as well [ 6 , 7 , 8 ]. However, in the absence of formal guidance, studies that report on research differ substantially in how they are named, conducted and reported [ 9 , 10 ]. This creates challenges in identifying, summarizing and comparing them. In this tutorial paper, we will use the term methodological study to refer to any study that reports on the design, conduct, analysis or reporting of primary or secondary research-related reports (such as trial registry entries and conference abstracts).

In the past 10 years, there has been an increase in the use of terms related to methodological studies (based on records retrieved with a keyword search [in the title and abstract] for “methodological review” and “meta-epidemiological study” in PubMed up to December 2019), suggesting that these studies may be appearing more frequently in the literature. See Fig.  1 .

Trends in the number studies that mention “methodological review” or “meta-

epidemiological study” in PubMed.

The methods used in many methodological studies have been borrowed from systematic and scoping reviews. This practice has influenced the direction of the field, with many methodological studies including searches of electronic databases, screening of records, duplicate data extraction and assessments of risk of bias in the included studies. However, the research questions posed in methodological studies do not always require the approaches listed above, and guidance is needed on when and how to apply these methods to a methodological study. Even though methodological studies can be conducted on qualitative or mixed methods research, this paper focuses on and draws examples exclusively from quantitative research.

The objectives of this paper are to provide some insights on how to conduct methodological studies so that there is greater consistency between the research questions posed, and the design, analysis and reporting of findings. We provide multiple examples to illustrate concepts and a proposed framework for categorizing methodological studies in quantitative research.

What is a methodological study?

Any study that describes or analyzes methods (design, conduct, analysis or reporting) in published (or unpublished) literature is a methodological study. Consequently, the scope of methodological studies is quite extensive and includes, but is not limited to, topics as diverse as: research question formulation [ 11 ]; adherence to reporting guidelines [ 12 , 13 , 14 ] and consistency in reporting [ 15 ]; approaches to study analysis [ 16 ]; investigating the credibility of analyses [ 17 ]; and studies that synthesize these methodological studies [ 18 ]. While the nomenclature of methodological studies is not uniform, the intents and purposes of these studies remain fairly consistent – to describe or analyze methods in primary or secondary studies. As such, methodological studies may also be classified as a subtype of observational studies.

Parallel to this are experimental studies that compare different methods. Even though they play an important role in informing optimal research methods, experimental methodological studies are beyond the scope of this paper. Examples of such studies include the randomized trials by Buscemi et al., comparing single data extraction to double data extraction [ 19 ], and Carrasco-Labra et al., comparing approaches to presenting findings in Grading of Recommendations, Assessment, Development and Evaluations (GRADE) summary of findings tables [ 20 ]. In these studies, the unit of analysis is the person or groups of individuals applying the methods. We also direct readers to the Studies Within a Trial (SWAT) and Studies Within a Review (SWAR) programme operated through the Hub for Trials Methodology Research, for further reading as a potential useful resource for these types of experimental studies [ 21 ]. Lastly, this paper is not meant to inform the conduct of research using computational simulation and mathematical modeling for which some guidance already exists [ 22 ], or studies on the development of methods using consensus-based approaches.

When should we conduct a methodological study?

Methodological studies occupy a unique niche in health research that allows them to inform methodological advances. Methodological studies should also be conducted as pre-cursors to reporting guideline development, as they provide an opportunity to understand current practices, and help to identify the need for guidance and gaps in methodological or reporting quality. For example, the development of the popular Preferred Reporting Items of Systematic reviews and Meta-Analyses (PRISMA) guidelines were preceded by methodological studies identifying poor reporting practices [ 23 , 24 ]. In these instances, after the reporting guidelines are published, methodological studies can also be used to monitor uptake of the guidelines.

These studies can also be conducted to inform the state of the art for design, analysis and reporting practices across different types of health research fields, with the aim of improving research practices, and preventing or reducing research waste. For example, Samaan et al. conducted a scoping review of adherence to different reporting guidelines in health care literature [ 18 ]. Methodological studies can also be used to determine the factors associated with reporting practices. For example, Abbade et al. investigated journal characteristics associated with the use of the Participants, Intervention, Comparison, Outcome, Timeframe (PICOT) format in framing research questions in trials of venous ulcer disease [ 11 ].

How often are methodological studies conducted?

There is no clear answer to this question. Based on a search of PubMed, the use of related terms (“methodological review” and “meta-epidemiological study”) – and therefore, the number of methodological studies – is on the rise. However, many other terms are used to describe methodological studies. There are also many studies that explore design, conduct, analysis or reporting of research reports, but that do not use any specific terms to describe or label their study design in terms of “methodology”. This diversity in nomenclature makes a census of methodological studies elusive. Appropriate terminology and key words for methodological studies are needed to facilitate improved accessibility for end-users.

Why do we conduct methodological studies?

Methodological studies provide information on the design, conduct, analysis or reporting of primary and secondary research and can be used to appraise quality, quantity, completeness, accuracy and consistency of health research. These issues can be explored in specific fields, journals, databases, geographical regions and time periods. For example, Areia et al. explored the quality of reporting of endoscopic diagnostic studies in gastroenterology [ 25 ]; Knol et al. investigated the reporting of p -values in baseline tables in randomized trial published in high impact journals [ 26 ]; Chen et al. describe adherence to the Consolidated Standards of Reporting Trials (CONSORT) statement in Chinese Journals [ 27 ]; and Hopewell et al. describe the effect of editors’ implementation of CONSORT guidelines on reporting of abstracts over time [ 28 ]. Methodological studies provide useful information to researchers, clinicians, editors, publishers and users of health literature. As a result, these studies have been at the cornerstone of important methodological developments in the past two decades and have informed the development of many health research guidelines including the highly cited CONSORT statement [ 5 ].

Where can we find methodological studies?

Methodological studies can be found in most common biomedical bibliographic databases (e.g. Embase, MEDLINE, PubMed, Web of Science). However, the biggest caveat is that methodological studies are hard to identify in the literature due to the wide variety of names used and the lack of comprehensive databases dedicated to them. A handful can be found in the Cochrane Library as “Cochrane Methodology Reviews”, but these studies only cover methodological issues related to systematic reviews. Previous attempts to catalogue all empirical studies of methods used in reviews were abandoned 10 years ago [ 29 ]. In other databases, a variety of search terms may be applied with different levels of sensitivity and specificity.

Some frequently asked questions about methodological studies

In this section, we have outlined responses to questions that might help inform the conduct of methodological studies.

Q: How should I select research reports for my methodological study?

A: Selection of research reports for a methodological study depends on the research question and eligibility criteria. Once a clear research question is set and the nature of literature one desires to review is known, one can then begin the selection process. Selection may begin with a broad search, especially if the eligibility criteria are not apparent. For example, a methodological study of Cochrane Reviews of HIV would not require a complex search as all eligible studies can easily be retrieved from the Cochrane Library after checking a few boxes [ 30 ]. On the other hand, a methodological study of subgroup analyses in trials of gastrointestinal oncology would require a search to find such trials, and further screening to identify trials that conducted a subgroup analysis [ 31 ].

The strategies used for identifying participants in observational studies can apply here. One may use a systematic search to identify all eligible studies. If the number of eligible studies is unmanageable, a random sample of articles can be expected to provide comparable results if it is sufficiently large [ 32 ]. For example, Wilson et al. used a random sample of trials from the Cochrane Stroke Group’s Trial Register to investigate completeness of reporting [ 33 ]. It is possible that a simple random sample would lead to underrepresentation of units (i.e. research reports) that are smaller in number. This is relevant if the investigators wish to compare multiple groups but have too few units in one group. In this case a stratified sample would help to create equal groups. For example, in a methodological study comparing Cochrane and non-Cochrane reviews, Kahale et al. drew random samples from both groups [ 34 ]. Alternatively, systematic or purposeful sampling strategies can be used and we encourage researchers to justify their selected approaches based on the study objective.

Q: How many databases should I search?

A: The number of databases one should search would depend on the approach to sampling, which can include targeting the entire “population” of interest or a sample of that population. If you are interested in including the entire target population for your research question, or drawing a random or systematic sample from it, then a comprehensive and exhaustive search for relevant articles is required. In this case, we recommend using systematic approaches for searching electronic databases (i.e. at least 2 databases with a replicable and time stamped search strategy). The results of your search will constitute a sampling frame from which eligible studies can be drawn.

Alternatively, if your approach to sampling is purposeful, then we recommend targeting the database(s) or data sources (e.g. journals, registries) that include the information you need. For example, if you are conducting a methodological study of high impact journals in plastic surgery and they are all indexed in PubMed, you likely do not need to search any other databases. You may also have a comprehensive list of all journals of interest and can approach your search using the journal names in your database search (or by accessing the journal archives directly from the journal’s website). Even though one could also search journals’ web pages directly, using a database such as PubMed has multiple advantages, such as the use of filters, so the search can be narrowed down to a certain period, or study types of interest. Furthermore, individual journals’ web sites may have different search functionalities, which do not necessarily yield a consistent output.

Q: Should I publish a protocol for my methodological study?

A: A protocol is a description of intended research methods. Currently, only protocols for clinical trials require registration [ 35 ]. Protocols for systematic reviews are encouraged but no formal recommendation exists. The scientific community welcomes the publication of protocols because they help protect against selective outcome reporting, the use of post hoc methodologies to embellish results, and to help avoid duplication of efforts [ 36 ]. While the latter two risks exist in methodological research, the negative consequences may be substantially less than for clinical outcomes. In a sample of 31 methodological studies, 7 (22.6%) referenced a published protocol [ 9 ]. In the Cochrane Library, there are 15 protocols for methodological reviews (21 July 2020). This suggests that publishing protocols for methodological studies is not uncommon.

Authors can consider publishing their study protocol in a scholarly journal as a manuscript. Advantages of such publication include obtaining peer-review feedback about the planned study, and easy retrieval by searching databases such as PubMed. The disadvantages in trying to publish protocols includes delays associated with manuscript handling and peer review, as well as costs, as few journals publish study protocols, and those journals mostly charge article-processing fees [ 37 ]. Authors who would like to make their protocol publicly available without publishing it in scholarly journals, could deposit their study protocols in publicly available repositories, such as the Open Science Framework ( https://osf.io/ ).

Q: How to appraise the quality of a methodological study?

A: To date, there is no published tool for appraising the risk of bias in a methodological study, but in principle, a methodological study could be considered as a type of observational study. Therefore, during conduct or appraisal, care should be taken to avoid the biases common in observational studies [ 38 ]. These biases include selection bias, comparability of groups, and ascertainment of exposure or outcome. In other words, to generate a representative sample, a comprehensive reproducible search may be necessary to build a sampling frame. Additionally, random sampling may be necessary to ensure that all the included research reports have the same probability of being selected, and the screening and selection processes should be transparent and reproducible. To ensure that the groups compared are similar in all characteristics, matching, random sampling or stratified sampling can be used. Statistical adjustments for between-group differences can also be applied at the analysis stage. Finally, duplicate data extraction can reduce errors in assessment of exposures or outcomes.

Q: Should I justify a sample size?

A: In all instances where one is not using the target population (i.e. the group to which inferences from the research report are directed) [ 39 ], a sample size justification is good practice. The sample size justification may take the form of a description of what is expected to be achieved with the number of articles selected, or a formal sample size estimation that outlines the number of articles required to answer the research question with a certain precision and power. Sample size justifications in methodological studies are reasonable in the following instances:

Comparing two groups

Determining a proportion, mean or another quantifier

Determining factors associated with an outcome using regression-based analyses

For example, El Dib et al. computed a sample size requirement for a methodological study of diagnostic strategies in randomized trials, based on a confidence interval approach [ 40 ].

Q: What should I call my study?

A: Other terms which have been used to describe/label methodological studies include “ methodological review ”, “methodological survey” , “meta-epidemiological study” , “systematic review” , “systematic survey”, “meta-research”, “research-on-research” and many others. We recommend that the study nomenclature be clear, unambiguous, informative and allow for appropriate indexing. Methodological study nomenclature that should be avoided includes “ systematic review” – as this will likely be confused with a systematic review of a clinical question. “ Systematic survey” may also lead to confusion about whether the survey was systematic (i.e. using a preplanned methodology) or a survey using “ systematic” sampling (i.e. a sampling approach using specific intervals to determine who is selected) [ 32 ]. Any of the above meanings of the words “ systematic” may be true for methodological studies and could be potentially misleading. “ Meta-epidemiological study” is ideal for indexing, but not very informative as it describes an entire field. The term “ review ” may point towards an appraisal or “review” of the design, conduct, analysis or reporting (or methodological components) of the targeted research reports, yet it has also been used to describe narrative reviews [ 41 , 42 ]. The term “ survey ” is also in line with the approaches used in many methodological studies [ 9 ], and would be indicative of the sampling procedures of this study design. However, in the absence of guidelines on nomenclature, the term “ methodological study ” is broad enough to capture most of the scenarios of such studies.

Q: Should I account for clustering in my methodological study?

A: Data from methodological studies are often clustered. For example, articles coming from a specific source may have different reporting standards (e.g. the Cochrane Library). Articles within the same journal may be similar due to editorial practices and policies, reporting requirements and endorsement of guidelines. There is emerging evidence that these are real concerns that should be accounted for in analyses [ 43 ]. Some cluster variables are described in the section: “ What variables are relevant to methodological studies?”

A variety of modelling approaches can be used to account for correlated data, including the use of marginal, fixed or mixed effects regression models with appropriate computation of standard errors [ 44 ]. For example, Kosa et al. used generalized estimation equations to account for correlation of articles within journals [ 15 ]. Not accounting for clustering could lead to incorrect p -values, unduly narrow confidence intervals, and biased estimates [ 45 ].

Q: Should I extract data in duplicate?

A: Yes. Duplicate data extraction takes more time but results in less errors [ 19 ]. Data extraction errors in turn affect the effect estimate [ 46 ], and therefore should be mitigated. Duplicate data extraction should be considered in the absence of other approaches to minimize extraction errors. However, much like systematic reviews, this area will likely see rapid new advances with machine learning and natural language processing technologies to support researchers with screening and data extraction [ 47 , 48 ]. However, experience plays an important role in the quality of extracted data and inexperienced extractors should be paired with experienced extractors [ 46 , 49 ].

Q: Should I assess the risk of bias of research reports included in my methodological study?

A : Risk of bias is most useful in determining the certainty that can be placed in the effect measure from a study. In methodological studies, risk of bias may not serve the purpose of determining the trustworthiness of results, as effect measures are often not the primary goal of methodological studies. Determining risk of bias in methodological studies is likely a practice borrowed from systematic review methodology, but whose intrinsic value is not obvious in methodological studies. When it is part of the research question, investigators often focus on one aspect of risk of bias. For example, Speich investigated how blinding was reported in surgical trials [ 50 ], and Abraha et al., investigated the application of intention-to-treat analyses in systematic reviews and trials [ 51 ].

Q: What variables are relevant to methodological studies?

A: There is empirical evidence that certain variables may inform the findings in a methodological study. We outline some of these and provide a brief overview below:

Country: Countries and regions differ in their research cultures, and the resources available to conduct research. Therefore, it is reasonable to believe that there may be differences in methodological features across countries. Methodological studies have reported loco-regional differences in reporting quality [ 52 , 53 ]. This may also be related to challenges non-English speakers face in publishing papers in English.

Authors’ expertise: The inclusion of authors with expertise in research methodology, biostatistics, and scientific writing is likely to influence the end-product. Oltean et al. found that among randomized trials in orthopaedic surgery, the use of analyses that accounted for clustering was more likely when specialists (e.g. statistician, epidemiologist or clinical trials methodologist) were included on the study team [ 54 ]. Fleming et al. found that including methodologists in the review team was associated with appropriate use of reporting guidelines [ 55 ].

Source of funding and conflicts of interest: Some studies have found that funded studies report better [ 56 , 57 ], while others do not [ 53 , 58 ]. The presence of funding would indicate the availability of resources deployed to ensure optimal design, conduct, analysis and reporting. However, the source of funding may introduce conflicts of interest and warrant assessment. For example, Kaiser et al. investigated the effect of industry funding on obesity or nutrition randomized trials and found that reporting quality was similar [ 59 ]. Thomas et al. looked at reporting quality of long-term weight loss trials and found that industry funded studies were better [ 60 ]. Kan et al. examined the association between industry funding and “positive trials” (trials reporting a significant intervention effect) and found that industry funding was highly predictive of a positive trial [ 61 ]. This finding is similar to that of a recent Cochrane Methodology Review by Hansen et al. [ 62 ]

Journal characteristics: Certain journals’ characteristics may influence the study design, analysis or reporting. Characteristics such as journal endorsement of guidelines [ 63 , 64 ], and Journal Impact Factor (JIF) have been shown to be associated with reporting [ 63 , 65 , 66 , 67 ].

Study size (sample size/number of sites): Some studies have shown that reporting is better in larger studies [ 53 , 56 , 58 ].

Year of publication: It is reasonable to assume that design, conduct, analysis and reporting of research will change over time. Many studies have demonstrated improvements in reporting over time or after the publication of reporting guidelines [ 68 , 69 ].

Type of intervention: In a methodological study of reporting quality of weight loss intervention studies, Thabane et al. found that trials of pharmacologic interventions were reported better than trials of non-pharmacologic interventions [ 70 ].

Interactions between variables: Complex interactions between the previously listed variables are possible. High income countries with more resources may be more likely to conduct larger studies and incorporate a variety of experts. Authors in certain countries may prefer certain journals, and journal endorsement of guidelines and editorial policies may change over time.

Q: Should I focus only on high impact journals?

A: Investigators may choose to investigate only high impact journals because they are more likely to influence practice and policy, or because they assume that methodological standards would be higher. However, the JIF may severely limit the scope of articles included and may skew the sample towards articles with positive findings. The generalizability and applicability of findings from a handful of journals must be examined carefully, especially since the JIF varies over time. Even among journals that are all “high impact”, variations exist in methodological standards.

Q: Can I conduct a methodological study of qualitative research?

A: Yes. Even though a lot of methodological research has been conducted in the quantitative research field, methodological studies of qualitative studies are feasible. Certain databases that catalogue qualitative research including the Cumulative Index to Nursing & Allied Health Literature (CINAHL) have defined subject headings that are specific to methodological research (e.g. “research methodology”). Alternatively, one could also conduct a qualitative methodological review; that is, use qualitative approaches to synthesize methodological issues in qualitative studies.

Q: What reporting guidelines should I use for my methodological study?

A: There is no guideline that covers the entire scope of methodological studies. One adaptation of the PRISMA guidelines has been published, which works well for studies that aim to use the entire target population of research reports [ 71 ]. However, it is not widely used (40 citations in 2 years as of 09 December 2019), and methodological studies that are designed as cross-sectional or before-after studies require a more fit-for purpose guideline. A more encompassing reporting guideline for a broad range of methodological studies is currently under development [ 72 ]. However, in the absence of formal guidance, the requirements for scientific reporting should be respected, and authors of methodological studies should focus on transparency and reproducibility.

Q: What are the potential threats to validity and how can I avoid them?

A: Methodological studies may be compromised by a lack of internal or external validity. The main threats to internal validity in methodological studies are selection and confounding bias. Investigators must ensure that the methods used to select articles does not make them differ systematically from the set of articles to which they would like to make inferences. For example, attempting to make extrapolations to all journals after analyzing high-impact journals would be misleading.

Many factors (confounders) may distort the association between the exposure and outcome if the included research reports differ with respect to these factors [ 73 ]. For example, when examining the association between source of funding and completeness of reporting, it may be necessary to account for journals that endorse the guidelines. Confounding bias can be addressed by restriction, matching and statistical adjustment [ 73 ]. Restriction appears to be the method of choice for many investigators who choose to include only high impact journals or articles in a specific field. For example, Knol et al. examined the reporting of p -values in baseline tables of high impact journals [ 26 ]. Matching is also sometimes used. In the methodological study of non-randomized interventional studies of elective ventral hernia repair, Parker et al. matched prospective studies with retrospective studies and compared reporting standards [ 74 ]. Some other methodological studies use statistical adjustments. For example, Zhang et al. used regression techniques to determine the factors associated with missing participant data in trials [ 16 ].

With regard to external validity, researchers interested in conducting methodological studies must consider how generalizable or applicable their findings are. This should tie in closely with the research question and should be explicit. For example. Findings from methodological studies on trials published in high impact cardiology journals cannot be assumed to be applicable to trials in other fields. However, investigators must ensure that their sample truly represents the target sample either by a) conducting a comprehensive and exhaustive search, or b) using an appropriate and justified, randomly selected sample of research reports.

Even applicability to high impact journals may vary based on the investigators’ definition, and over time. For example, for high impact journals in the field of general medicine, Bouwmeester et al. included the Annals of Internal Medicine (AIM), BMJ, the Journal of the American Medical Association (JAMA), Lancet, the New England Journal of Medicine (NEJM), and PLoS Medicine ( n  = 6) [ 75 ]. In contrast, the high impact journals selected in the methodological study by Schiller et al. were BMJ, JAMA, Lancet, and NEJM ( n  = 4) [ 76 ]. Another methodological study by Kosa et al. included AIM, BMJ, JAMA, Lancet and NEJM ( n  = 5). In the methodological study by Thabut et al., journals with a JIF greater than 5 were considered to be high impact. Riado Minguez et al. used first quartile journals in the Journal Citation Reports (JCR) for a specific year to determine “high impact” [ 77 ]. Ultimately, the definition of high impact will be based on the number of journals the investigators are willing to include, the year of impact and the JIF cut-off [ 78 ]. We acknowledge that the term “generalizability” may apply differently for methodological studies, especially when in many instances it is possible to include the entire target population in the sample studied.

Finally, methodological studies are not exempt from information bias which may stem from discrepancies in the included research reports [ 79 ], errors in data extraction, or inappropriate interpretation of the information extracted. Likewise, publication bias may also be a concern in methodological studies, but such concepts have not yet been explored.

A proposed framework

In order to inform discussions about methodological studies, the development of guidance for what should be reported, we have outlined some key features of methodological studies that can be used to classify them. For each of the categories outlined below, we provide an example. In our experience, the choice of approach to completing a methodological study can be informed by asking the following four questions:

What is the aim?

Methodological studies that investigate bias

A methodological study may be focused on exploring sources of bias in primary or secondary studies (meta-bias), or how bias is analyzed. We have taken care to distinguish bias (i.e. systematic deviations from the truth irrespective of the source) from reporting quality or completeness (i.e. not adhering to a specific reporting guideline or norm). An example of where this distinction would be important is in the case of a randomized trial with no blinding. This study (depending on the nature of the intervention) would be at risk of performance bias. However, if the authors report that their study was not blinded, they would have reported adequately. In fact, some methodological studies attempt to capture both “quality of conduct” and “quality of reporting”, such as Richie et al., who reported on the risk of bias in randomized trials of pharmacy practice interventions [ 80 ]. Babic et al. investigated how risk of bias was used to inform sensitivity analyses in Cochrane reviews [ 81 ]. Further, biases related to choice of outcomes can also be explored. For example, Tan et al investigated differences in treatment effect size based on the outcome reported [ 82 ].

Methodological studies that investigate quality (or completeness) of reporting

Methodological studies may report quality of reporting against a reporting checklist (i.e. adherence to guidelines) or against expected norms. For example, Croituro et al. report on the quality of reporting in systematic reviews published in dermatology journals based on their adherence to the PRISMA statement [ 83 ], and Khan et al. described the quality of reporting of harms in randomized controlled trials published in high impact cardiovascular journals based on the CONSORT extension for harms [ 84 ]. Other methodological studies investigate reporting of certain features of interest that may not be part of formally published checklists or guidelines. For example, Mbuagbaw et al. described how often the implications for research are elaborated using the Evidence, Participants, Intervention, Comparison, Outcome, Timeframe (EPICOT) format [ 30 ].

Methodological studies that investigate the consistency of reporting

Sometimes investigators may be interested in how consistent reports of the same research are, as it is expected that there should be consistency between: conference abstracts and published manuscripts; manuscript abstracts and manuscript main text; and trial registration and published manuscript. For example, Rosmarakis et al. investigated consistency between conference abstracts and full text manuscripts [ 85 ].

Methodological studies that investigate factors associated with reporting

In addition to identifying issues with reporting in primary and secondary studies, authors of methodological studies may be interested in determining the factors that are associated with certain reporting practices. Many methodological studies incorporate this, albeit as a secondary outcome. For example, Farrokhyar et al. investigated the factors associated with reporting quality in randomized trials of coronary artery bypass grafting surgery [ 53 ].

Methodological studies that investigate methods

Methodological studies may also be used to describe methods or compare methods, and the factors associated with methods. Muller et al. described the methods used for systematic reviews and meta-analyses of observational studies [ 86 ].

Methodological studies that summarize other methodological studies

Some methodological studies synthesize results from other methodological studies. For example, Li et al. conducted a scoping review of methodological reviews that investigated consistency between full text and abstracts in primary biomedical research [ 87 ].

Methodological studies that investigate nomenclature and terminology

Some methodological studies may investigate the use of names and terms in health research. For example, Martinic et al. investigated the definitions of systematic reviews used in overviews of systematic reviews (OSRs), meta-epidemiological studies and epidemiology textbooks [ 88 ].

Other types of methodological studies

In addition to the previously mentioned experimental methodological studies, there may exist other types of methodological studies not captured here.

What is the design?

Methodological studies that are descriptive

Most methodological studies are purely descriptive and report their findings as counts (percent) and means (standard deviation) or medians (interquartile range). For example, Mbuagbaw et al. described the reporting of research recommendations in Cochrane HIV systematic reviews [ 30 ]. Gohari et al. described the quality of reporting of randomized trials in diabetes in Iran [ 12 ].

Methodological studies that are analytical

Some methodological studies are analytical wherein “analytical studies identify and quantify associations, test hypotheses, identify causes and determine whether an association exists between variables, such as between an exposure and a disease.” [ 89 ] In the case of methodological studies all these investigations are possible. For example, Kosa et al. investigated the association between agreement in primary outcome from trial registry to published manuscript and study covariates. They found that larger and more recent studies were more likely to have agreement [ 15 ]. Tricco et al. compared the conclusion statements from Cochrane and non-Cochrane systematic reviews with a meta-analysis of the primary outcome and found that non-Cochrane reviews were more likely to report positive findings. These results are a test of the null hypothesis that the proportions of Cochrane and non-Cochrane reviews that report positive results are equal [ 90 ].

What is the sampling strategy?

Methodological studies that include the target population

Methodological reviews with narrow research questions may be able to include the entire target population. For example, in the methodological study of Cochrane HIV systematic reviews, Mbuagbaw et al. included all of the available studies ( n  = 103) [ 30 ].

Methodological studies that include a sample of the target population

Many methodological studies use random samples of the target population [ 33 , 91 , 92 ]. Alternatively, purposeful sampling may be used, limiting the sample to a subset of research-related reports published within a certain time period, or in journals with a certain ranking or on a topic. Systematic sampling can also be used when random sampling may be challenging to implement.

What is the unit of analysis?

Methodological studies with a research report as the unit of analysis

Many methodological studies use a research report (e.g. full manuscript of study, abstract portion of the study) as the unit of analysis, and inferences can be made at the study-level. However, both published and unpublished research-related reports can be studied. These may include articles, conference abstracts, registry entries etc.

Methodological studies with a design, analysis or reporting item as the unit of analysis

Some methodological studies report on items which may occur more than once per article. For example, Paquette et al. report on subgroup analyses in Cochrane reviews of atrial fibrillation in which 17 systematic reviews planned 56 subgroup analyses [ 93 ].

This framework is outlined in Fig.  2 .

A proposed framework for methodological studies

Conclusions

Methodological studies have examined different aspects of reporting such as quality, completeness, consistency and adherence to reporting guidelines. As such, many of the methodological study examples cited in this tutorial are related to reporting. However, as an evolving field, the scope of research questions that can be addressed by methodological studies is expected to increase.

In this paper we have outlined the scope and purpose of methodological studies, along with examples of instances in which various approaches have been used. In the absence of formal guidance on the design, conduct, analysis and reporting of methodological studies, we have provided some advice to help make methodological studies consistent. This advice is grounded in good contemporary scientific practice. Generally, the research question should tie in with the sampling approach and planned analysis. We have also highlighted the variables that may inform findings from methodological studies. Lastly, we have provided suggestions for ways in which authors can categorize their methodological studies to inform their design and analysis.

Availability of data and materials

Data sharing is not applicable to this article as no new data were created or analyzed in this study.

Abbreviations

Consolidated Standards of Reporting Trials

Evidence, Participants, Intervention, Comparison, Outcome, Timeframe

Grading of Recommendations, Assessment, Development and Evaluations

Participants, Intervention, Comparison, Outcome, Timeframe

Preferred Reporting Items of Systematic reviews and Meta-Analyses

Studies Within a Review

Studies Within a Trial

Chalmers I, Glasziou P. Avoidable waste in the production and reporting of research evidence. Lancet. 2009;374(9683):86–9.

PubMed   Google Scholar  

Chan AW, Song F, Vickers A, Jefferson T, Dickersin K, Gotzsche PC, Krumholz HM, Ghersi D, van der Worp HB. Increasing value and reducing waste: addressing inaccessible research. Lancet. 2014;383(9913):257–66.

PubMed   PubMed Central   Google Scholar  

Ioannidis JP, Greenland S, Hlatky MA, Khoury MJ, Macleod MR, Moher D, Schulz KF, Tibshirani R. Increasing value and reducing waste in research design, conduct, and analysis. Lancet. 2014;383(9912):166–75.

Higgins JP, Altman DG, Gotzsche PC, Juni P, Moher D, Oxman AD, Savovic J, Schulz KF, Weeks L, Sterne JA. The Cochrane Collaboration's tool for assessing risk of bias in randomised trials. BMJ. 2011;343:d5928.

Moher D, Schulz KF, Altman DG. The CONSORT statement: revised recommendations for improving the quality of reports of parallel-group randomised trials. Lancet. 2001;357.

Liberati A, Altman DG, Tetzlaff J, Mulrow C, Gotzsche PC, Ioannidis JP, Clarke M, Devereaux PJ, Kleijnen J, Moher D. The PRISMA statement for reporting systematic reviews and meta-analyses of studies that evaluate health care interventions: explanation and elaboration. PLoS Med. 2009;6(7):e1000100.

Shea BJ, Hamel C, Wells GA, Bouter LM, Kristjansson E, Grimshaw J, Henry DA, Boers M. AMSTAR is a reliable and valid measurement tool to assess the methodological quality of systematic reviews. J Clin Epidemiol. 2009;62(10):1013–20.

Shea BJ, Reeves BC, Wells G, Thuku M, Hamel C, Moran J, Moher D, Tugwell P, Welch V, Kristjansson E, et al. AMSTAR 2: a critical appraisal tool for systematic reviews that include randomised or non-randomised studies of healthcare interventions, or both. Bmj. 2017;358:j4008.

Lawson DO, Leenus A, Mbuagbaw L. Mapping the nomenclature, methodology, and reporting of studies that review methods: a pilot methodological review. Pilot Feasibility Studies. 2020;6(1):13.

Puljak L, Makaric ZL, Buljan I, Pieper D. What is a meta-epidemiological study? Analysis of published literature indicated heterogeneous study designs and definitions. J Comp Eff Res. 2020.

Abbade LPF, Wang M, Sriganesh K, Jin Y, Mbuagbaw L, Thabane L. The framing of research questions using the PICOT format in randomized controlled trials of venous ulcer disease is suboptimal: a systematic survey. Wound Repair Regen. 2017;25(5):892–900.

Gohari F, Baradaran HR, Tabatabaee M, Anijidani S, Mohammadpour Touserkani F, Atlasi R, Razmgir M. Quality of reporting randomized controlled trials (RCTs) in diabetes in Iran; a systematic review. J Diabetes Metab Disord. 2015;15(1):36.

Wang M, Jin Y, Hu ZJ, Thabane A, Dennis B, Gajic-Veljanoski O, Paul J, Thabane L. The reporting quality of abstracts of stepped wedge randomized trials is suboptimal: a systematic survey of the literature. Contemp Clin Trials Commun. 2017;8:1–10.

Shanthanna H, Kaushal A, Mbuagbaw L, Couban R, Busse J, Thabane L: A cross-sectional study of the reporting quality of pilot or feasibility trials in high-impact anesthesia journals Can J Anaesthesia 2018, 65(11):1180–1195.

Kosa SD, Mbuagbaw L, Borg Debono V, Bhandari M, Dennis BB, Ene G, Leenus A, Shi D, Thabane M, Valvasori S, et al. Agreement in reporting between trial publications and current clinical trial registry in high impact journals: a methodological review. Contemporary Clinical Trials. 2018;65:144–50.

Zhang Y, Florez ID, Colunga Lozano LE, Aloweni FAB, Kennedy SA, Li A, Craigie S, Zhang S, Agarwal A, Lopes LC, et al. A systematic survey on reporting and methods for handling missing participant data for continuous outcomes in randomized controlled trials. J Clin Epidemiol. 2017;88:57–66.

CAS   PubMed   Google Scholar  

Hernández AV, Boersma E, Murray GD, Habbema JD, Steyerberg EW. Subgroup analyses in therapeutic cardiovascular clinical trials: are most of them misleading? Am Heart J. 2006;151(2):257–64.

Samaan Z, Mbuagbaw L, Kosa D, Borg Debono V, Dillenburg R, Zhang S, Fruci V, Dennis B, Bawor M, Thabane L. A systematic scoping review of adherence to reporting guidelines in health care literature. J Multidiscip Healthc. 2013;6:169–88.

Buscemi N, Hartling L, Vandermeer B, Tjosvold L, Klassen TP. Single data extraction generated more errors than double data extraction in systematic reviews. J Clin Epidemiol. 2006;59(7):697–703.

Carrasco-Labra A, Brignardello-Petersen R, Santesso N, Neumann I, Mustafa RA, Mbuagbaw L, Etxeandia Ikobaltzeta I, De Stio C, McCullagh LJ, Alonso-Coello P. Improving GRADE evidence tables part 1: a randomized trial shows improved understanding of content in summary-of-findings tables with a new format. J Clin Epidemiol. 2016;74:7–18.

The Northern Ireland Hub for Trials Methodology Research: SWAT/SWAR Information [ https://www.qub.ac.uk/sites/TheNorthernIrelandNetworkforTrialsMethodologyResearch/SWATSWARInformation/ ]. Accessed 31 Aug 2020.

Chick S, Sánchez P, Ferrin D, Morrice D. How to conduct a successful simulation study. In: Proceedings of the 2003 winter simulation conference: 2003; 2003. p. 66–70.

Google Scholar  

Mulrow CD. The medical review article: state of the science. Ann Intern Med. 1987;106(3):485–8.

Sacks HS, Reitman D, Pagano D, Kupelnick B. Meta-analysis: an update. Mount Sinai J Med New York. 1996;63(3–4):216–24.

CAS   Google Scholar  

Areia M, Soares M, Dinis-Ribeiro M. Quality reporting of endoscopic diagnostic studies in gastrointestinal journals: where do we stand on the use of the STARD and CONSORT statements? Endoscopy. 2010;42(2):138–47.

Knol M, Groenwold R, Grobbee D. P-values in baseline tables of randomised controlled trials are inappropriate but still common in high impact journals. Eur J Prev Cardiol. 2012;19(2):231–2.

Chen M, Cui J, Zhang AL, Sze DM, Xue CC, May BH. Adherence to CONSORT items in randomized controlled trials of integrative medicine for colorectal Cancer published in Chinese journals. J Altern Complement Med. 2018;24(2):115–24.

Hopewell S, Ravaud P, Baron G, Boutron I. Effect of editors' implementation of CONSORT guidelines on the reporting of abstracts in high impact medical journals: interrupted time series analysis. BMJ. 2012;344:e4178.

The Cochrane Methodology Register Issue 2 2009 [ https://cmr.cochrane.org/help.htm ]. Accessed 31 Aug 2020.

Mbuagbaw L, Kredo T, Welch V, Mursleen S, Ross S, Zani B, Motaze NV, Quinlan L. Critical EPICOT items were absent in Cochrane human immunodeficiency virus systematic reviews: a bibliometric analysis. J Clin Epidemiol. 2016;74:66–72.

Barton S, Peckitt C, Sclafani F, Cunningham D, Chau I. The influence of industry sponsorship on the reporting of subgroup analyses within phase III randomised controlled trials in gastrointestinal oncology. Eur J Cancer. 2015;51(18):2732–9.

Setia MS. Methodology series module 5: sampling strategies. Indian J Dermatol. 2016;61(5):505–9.

Wilson B, Burnett P, Moher D, Altman DG, Al-Shahi Salman R. Completeness of reporting of randomised controlled trials including people with transient ischaemic attack or stroke: a systematic review. Eur Stroke J. 2018;3(4):337–46.

Kahale LA, Diab B, Brignardello-Petersen R, Agarwal A, Mustafa RA, Kwong J, Neumann I, Li L, Lopes LC, Briel M, et al. Systematic reviews do not adequately report or address missing outcome data in their analyses: a methodological survey. J Clin Epidemiol. 2018;99:14–23.

De Angelis CD, Drazen JM, Frizelle FA, Haug C, Hoey J, Horton R, Kotzin S, Laine C, Marusic A, Overbeke AJPM, et al. Is this clinical trial fully registered?: a statement from the International Committee of Medical Journal Editors*. Ann Intern Med. 2005;143(2):146–8.

Ohtake PJ, Childs JD. Why publish study protocols? Phys Ther. 2014;94(9):1208–9.

Rombey T, Allers K, Mathes T, Hoffmann F, Pieper D. A descriptive analysis of the characteristics and the peer review process of systematic review protocols published in an open peer review journal from 2012 to 2017. BMC Med Res Methodol. 2019;19(1):57.

Grimes DA, Schulz KF. Bias and causal associations in observational research. Lancet. 2002;359(9302):248–52.

Porta M (ed.): A dictionary of epidemiology, 5th edn. Oxford: Oxford University Press, Inc.; 2008.

El Dib R, Tikkinen KAO, Akl EA, Gomaa HA, Mustafa RA, Agarwal A, Carpenter CR, Zhang Y, Jorge EC, Almeida R, et al. Systematic survey of randomized trials evaluating the impact of alternative diagnostic strategies on patient-important outcomes. J Clin Epidemiol. 2017;84:61–9.

Helzer JE, Robins LN, Taibleson M, Woodruff RA Jr, Reich T, Wish ED. Reliability of psychiatric diagnosis. I. a methodological review. Arch Gen Psychiatry. 1977;34(2):129–33.

Chung ST, Chacko SK, Sunehag AL, Haymond MW. Measurements of gluconeogenesis and Glycogenolysis: a methodological review. Diabetes. 2015;64(12):3996–4010.

CAS   PubMed   PubMed Central   Google Scholar  

Sterne JA, Juni P, Schulz KF, Altman DG, Bartlett C, Egger M. Statistical methods for assessing the influence of study characteristics on treatment effects in 'meta-epidemiological' research. Stat Med. 2002;21(11):1513–24.

Moen EL, Fricano-Kugler CJ, Luikart BW, O’Malley AJ. Analyzing clustered data: why and how to account for multiple observations nested within a study participant? PLoS One. 2016;11(1):e0146721.

Zyzanski SJ, Flocke SA, Dickinson LM. On the nature and analysis of clustered data. Ann Fam Med. 2004;2(3):199–200.

Mathes T, Klassen P, Pieper D. Frequency of data extraction errors and methods to increase data extraction quality: a methodological review. BMC Med Res Methodol. 2017;17(1):152.

Bui DDA, Del Fiol G, Hurdle JF, Jonnalagadda S. Extractive text summarization system to aid data extraction from full text in systematic review development. J Biomed Inform. 2016;64:265–72.

Bui DD, Del Fiol G, Jonnalagadda S. PDF text classification to leverage information extraction from publication reports. J Biomed Inform. 2016;61:141–8.

Maticic K, Krnic Martinic M, Puljak L. Assessment of reporting quality of abstracts of systematic reviews with meta-analysis using PRISMA-A and discordance in assessments between raters without prior experience. BMC Med Res Methodol. 2019;19(1):32.

Speich B. Blinding in surgical randomized clinical trials in 2015. Ann Surg. 2017;266(1):21–2.

Abraha I, Cozzolino F, Orso M, Marchesi M, Germani A, Lombardo G, Eusebi P, De Florio R, Luchetta ML, Iorio A, et al. A systematic review found that deviations from intention-to-treat are common in randomized trials and systematic reviews. J Clin Epidemiol. 2017;84:37–46.

Zhong Y, Zhou W, Jiang H, Fan T, Diao X, Yang H, Min J, Wang G, Fu J, Mao B. Quality of reporting of two-group parallel randomized controlled clinical trials of multi-herb formulae: A survey of reports indexed in the Science Citation Index Expanded. Eur J Integrative Med. 2011;3(4):e309–16.

Farrokhyar F, Chu R, Whitlock R, Thabane L. A systematic review of the quality of publications reporting coronary artery bypass grafting trials. Can J Surg. 2007;50(4):266–77.

Oltean H, Gagnier JJ. Use of clustering analysis in randomized controlled trials in orthopaedic surgery. BMC Med Res Methodol. 2015;15:17.

Fleming PS, Koletsi D, Pandis N. Blinded by PRISMA: are systematic reviewers focusing on PRISMA and ignoring other guidelines? PLoS One. 2014;9(5):e96407.

Balasubramanian SP, Wiener M, Alshameeri Z, Tiruvoipati R, Elbourne D, Reed MW. Standards of reporting of randomized controlled trials in general surgery: can we do better? Ann Surg. 2006;244(5):663–7.

de Vries TW, van Roon EN. Low quality of reporting adverse drug reactions in paediatric randomised controlled trials. Arch Dis Child. 2010;95(12):1023–6.

Borg Debono V, Zhang S, Ye C, Paul J, Arya A, Hurlburt L, Murthy Y, Thabane L. The quality of reporting of RCTs used within a postoperative pain management meta-analysis, using the CONSORT statement. BMC Anesthesiol. 2012;12:13.

Kaiser KA, Cofield SS, Fontaine KR, Glasser SP, Thabane L, Chu R, Ambrale S, Dwary AD, Kumar A, Nayyar G, et al. Is funding source related to study reporting quality in obesity or nutrition randomized control trials in top-tier medical journals? Int J Obes. 2012;36(7):977–81.

Thomas O, Thabane L, Douketis J, Chu R, Westfall AO, Allison DB. Industry funding and the reporting quality of large long-term weight loss trials. Int J Obes. 2008;32(10):1531–6.

Khan NR, Saad H, Oravec CS, Rossi N, Nguyen V, Venable GT, Lillard JC, Patel P, Taylor DR, Vaughn BN, et al. A review of industry funding in randomized controlled trials published in the neurosurgical literature-the elephant in the room. Neurosurgery. 2018;83(5):890–7.

Hansen C, Lundh A, Rasmussen K, Hrobjartsson A. Financial conflicts of interest in systematic reviews: associations with results, conclusions, and methodological quality. Cochrane Database Syst Rev. 2019;8:Mr000047.

Kiehna EN, Starke RM, Pouratian N, Dumont AS. Standards for reporting randomized controlled trials in neurosurgery. J Neurosurg. 2011;114(2):280–5.

Liu LQ, Morris PJ, Pengel LH. Compliance to the CONSORT statement of randomized controlled trials in solid organ transplantation: a 3-year overview. Transpl Int. 2013;26(3):300–6.

Bala MM, Akl EA, Sun X, Bassler D, Mertz D, Mejza F, Vandvik PO, Malaga G, Johnston BC, Dahm P, et al. Randomized trials published in higher vs. lower impact journals differ in design, conduct, and analysis. J Clin Epidemiol. 2013;66(3):286–95.

Lee SY, Teoh PJ, Camm CF, Agha RA. Compliance of randomized controlled trials in trauma surgery with the CONSORT statement. J Trauma Acute Care Surg. 2013;75(4):562–72.

Ziogas DC, Zintzaras E. Analysis of the quality of reporting of randomized controlled trials in acute and chronic myeloid leukemia, and myelodysplastic syndromes as governed by the CONSORT statement. Ann Epidemiol. 2009;19(7):494–500.

Alvarez F, Meyer N, Gourraud PA, Paul C. CONSORT adoption and quality of reporting of randomized controlled trials: a systematic analysis in two dermatology journals. Br J Dermatol. 2009;161(5):1159–65.

Mbuagbaw L, Thabane M, Vanniyasingam T, Borg Debono V, Kosa S, Zhang S, Ye C, Parpia S, Dennis BB, Thabane L. Improvement in the quality of abstracts in major clinical journals since CONSORT extension for abstracts: a systematic review. Contemporary Clin trials. 2014;38(2):245–50.

Thabane L, Chu R, Cuddy K, Douketis J. What is the quality of reporting in weight loss intervention studies? A systematic review of randomized controlled trials. Int J Obes. 2007;31(10):1554–9.

Murad MH, Wang Z. Guidelines for reporting meta-epidemiological methodology research. Evidence Based Med. 2017;22(4):139.

METRIC - MEthodological sTudy ReportIng Checklist: guidelines for reporting methodological studies in health research [ http://www.equator-network.org/library/reporting-guidelines-under-development/reporting-guidelines-under-development-for-other-study-designs/#METRIC ]. Accessed 31 Aug 2020.

Jager KJ, Zoccali C, MacLeod A, Dekker FW. Confounding: what it is and how to deal with it. Kidney Int. 2008;73(3):256–60.

Parker SG, Halligan S, Erotocritou M, Wood CPJ, Boulton RW, Plumb AAO, Windsor ACJ, Mallett S. A systematic methodological review of non-randomised interventional studies of elective ventral hernia repair: clear definitions and a standardised minimum dataset are needed. Hernia. 2019.

Bouwmeester W, Zuithoff NPA, Mallett S, Geerlings MI, Vergouwe Y, Steyerberg EW, Altman DG, Moons KGM. Reporting and methods in clinical prediction research: a systematic review. PLoS Med. 2012;9(5):1–12.

Schiller P, Burchardi N, Niestroj M, Kieser M. Quality of reporting of clinical non-inferiority and equivalence randomised trials--update and extension. Trials. 2012;13:214.

Riado Minguez D, Kowalski M, Vallve Odena M, Longin Pontzen D, Jelicic Kadic A, Jeric M, Dosenovic S, Jakus D, Vrdoljak M, Poklepovic Pericic T, et al. Methodological and reporting quality of systematic reviews published in the highest ranking journals in the field of pain. Anesth Analg. 2017;125(4):1348–54.

Thabut G, Estellat C, Boutron I, Samama CM, Ravaud P. Methodological issues in trials assessing primary prophylaxis of venous thrombo-embolism. Eur Heart J. 2005;27(2):227–36.

Puljak L, Riva N, Parmelli E, González-Lorenzo M, Moja L, Pieper D. Data extraction methods: an analysis of internal reporting discrepancies in single manuscripts and practical advice. J Clin Epidemiol. 2020;117:158–64.

Ritchie A, Seubert L, Clifford R, Perry D, Bond C. Do randomised controlled trials relevant to pharmacy meet best practice standards for quality conduct and reporting? A systematic review. Int J Pharm Pract. 2019.

Babic A, Vuka I, Saric F, Proloscic I, Slapnicar E, Cavar J, Pericic TP, Pieper D, Puljak L. Overall bias methods and their use in sensitivity analysis of Cochrane reviews were not consistent. J Clin Epidemiol. 2019.

Tan A, Porcher R, Crequit P, Ravaud P, Dechartres A. Differences in treatment effect size between overall survival and progression-free survival in immunotherapy trials: a Meta-epidemiologic study of trials with results posted at ClinicalTrials.gov. J Clin Oncol. 2017;35(15):1686–94.

Croitoru D, Huang Y, Kurdina A, Chan AW, Drucker AM. Quality of reporting in systematic reviews published in dermatology journals. Br J Dermatol. 2020;182(6):1469–76.

Khan MS, Ochani RK, Shaikh A, Vaduganathan M, Khan SU, Fatima K, Yamani N, Mandrola J, Doukky R, Krasuski RA: Assessing the Quality of Reporting of Harms in Randomized Controlled Trials Published in High Impact Cardiovascular Journals. Eur Heart J Qual Care Clin Outcomes 2019.

Rosmarakis ES, Soteriades ES, Vergidis PI, Kasiakou SK, Falagas ME. From conference abstract to full paper: differences between data presented in conferences and journals. FASEB J. 2005;19(7):673–80.

Mueller M, D’Addario M, Egger M, Cevallos M, Dekkers O, Mugglin C, Scott P. Methods to systematically review and meta-analyse observational studies: a systematic scoping review of recommendations. BMC Med Res Methodol. 2018;18(1):44.

Li G, Abbade LPF, Nwosu I, Jin Y, Leenus A, Maaz M, Wang M, Bhatt M, Zielinski L, Sanger N, et al. A scoping review of comparisons between abstracts and full reports in primary biomedical research. BMC Med Res Methodol. 2017;17(1):181.

Krnic Martinic M, Pieper D, Glatt A, Puljak L. Definition of a systematic review used in overviews of systematic reviews, meta-epidemiological studies and textbooks. BMC Med Res Methodol. 2019;19(1):203.

Analytical study [ https://medical-dictionary.thefreedictionary.com/analytical+study ]. Accessed 31 Aug 2020.

Tricco AC, Tetzlaff J, Pham B, Brehaut J, Moher D. Non-Cochrane vs. Cochrane reviews were twice as likely to have positive conclusion statements: cross-sectional study. J Clin Epidemiol. 2009;62(4):380–6 e381.

Schalken N, Rietbergen C. The reporting quality of systematic reviews and Meta-analyses in industrial and organizational psychology: a systematic review. Front Psychol. 2017;8:1395.

Ranker LR, Petersen JM, Fox MP. Awareness of and potential for dependent error in the observational epidemiologic literature: A review. Ann Epidemiol. 2019;36:15–9 e12.

Paquette M, Alotaibi AM, Nieuwlaat R, Santesso N, Mbuagbaw L. A meta-epidemiological study of subgroup analyses in cochrane systematic reviews of atrial fibrillation. Syst Rev. 2019;8(1):241.

Download references

Acknowledgements

This work did not receive any dedicated funding.

Author information

Authors and affiliations.

Department of Health Research Methods, Evidence and Impact, McMaster University, Hamilton, ON, Canada

Lawrence Mbuagbaw, Daeria O. Lawson & Lehana Thabane

Biostatistics Unit/FSORC, 50 Charlton Avenue East, St Joseph’s Healthcare—Hamilton, 3rd Floor Martha Wing, Room H321, Hamilton, Ontario, L8N 4A6, Canada

Lawrence Mbuagbaw & Lehana Thabane

Centre for the Development of Best Practices in Health, Yaoundé, Cameroon

Lawrence Mbuagbaw

Center for Evidence-Based Medicine and Health Care, Catholic University of Croatia, Ilica 242, 10000, Zagreb, Croatia

Livia Puljak

Department of Epidemiology and Biostatistics, School of Public Health – Bloomington, Indiana University, Bloomington, IN, 47405, USA

David B. Allison

Departments of Paediatrics and Anaesthesia, McMaster University, Hamilton, ON, Canada

Lehana Thabane

Centre for Evaluation of Medicine, St. Joseph’s Healthcare-Hamilton, Hamilton, ON, Canada

Population Health Research Institute, Hamilton Health Sciences, Hamilton, ON, Canada

You can also search for this author in PubMed   Google Scholar

Contributions

LM conceived the idea and drafted the outline and paper. DOL and LT commented on the idea and draft outline. LM, LP and DOL performed literature searches and data extraction. All authors (LM, DOL, LT, LP, DBA) reviewed several draft versions of the manuscript and approved the final manuscript.

Corresponding author

Correspondence to Lawrence Mbuagbaw .

Ethics declarations

Ethics approval and consent to participate.

Not applicable.

Consent for publication

Competing interests.

DOL, DBA, LM, LP and LT are involved in the development of a reporting guideline for methodological studies.

Additional information

Publisher’s note.

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/ . The Creative Commons Public Domain Dedication waiver ( http://creativecommons.org/publicdomain/zero/1.0/ ) applies to the data made available in this article, unless otherwise stated in a credit line to the data.

Reprints and permissions

About this article

Cite this article.

Mbuagbaw, L., Lawson, D.O., Puljak, L. et al. A tutorial on methodological studies: the what, when, how and why. BMC Med Res Methodol 20 , 226 (2020). https://doi.org/10.1186/s12874-020-01107-7

Download citation

Received : 27 May 2020

Accepted : 27 August 2020

Published : 07 September 2020

DOI : https://doi.org/10.1186/s12874-020-01107-7

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Methodological study
• Meta-epidemiology
• Research methods
• Research-on-research

BMC Medical Research Methodology

ISSN: 1471-2288

• General enquiries: [email protected]

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• J Korean Med Sci
• v.37(16); 2022 Apr 25

A Practical Guide to Writing Quantitative and Qualitative Research Questions and Hypotheses in Scholarly Articles

Edward barroga.

1 Department of General Education, Graduate School of Nursing Science, St. Luke’s International University, Tokyo, Japan.

Glafera Janet Matanguihan

2 Department of Biological Sciences, Messiah University, Mechanicsburg, PA, USA.

The development of research questions and the subsequent hypotheses are prerequisites to defining the main research purpose and specific objectives of a study. Consequently, these objectives determine the study design and research outcome. The development of research questions is a process based on knowledge of current trends, cutting-edge studies, and technological advances in the research field. Excellent research questions are focused and require a comprehensive literature search and in-depth understanding of the problem being investigated. Initially, research questions may be written as descriptive questions which could be developed into inferential questions. These questions must be specific and concise to provide a clear foundation for developing hypotheses. Hypotheses are more formal predictions about the research outcomes. These specify the possible results that may or may not be expected regarding the relationship between groups. Thus, research questions and hypotheses clarify the main purpose and specific objectives of the study, which in turn dictate the design of the study, its direction, and outcome. Studies developed from good research questions and hypotheses will have trustworthy outcomes with wide-ranging social and health implications.

INTRODUCTION

Scientific research is usually initiated by posing evidenced-based research questions which are then explicitly restated as hypotheses. 1 , 2 The hypotheses provide directions to guide the study, solutions, explanations, and expected results. 3 , 4 Both research questions and hypotheses are essentially formulated based on conventional theories and real-world processes, which allow the inception of novel studies and the ethical testing of ideas. 5 , 6

It is crucial to have knowledge of both quantitative and qualitative research 2 as both types of research involve writing research questions and hypotheses. 7 However, these crucial elements of research are sometimes overlooked; if not overlooked, then framed without the forethought and meticulous attention it needs. Planning and careful consideration are needed when developing quantitative or qualitative research, particularly when conceptualizing research questions and hypotheses. 4

There is a continuing need to support researchers in the creation of innovative research questions and hypotheses, as well as for journal articles that carefully review these elements. 1 When research questions and hypotheses are not carefully thought of, unethical studies and poor outcomes usually ensue. Carefully formulated research questions and hypotheses define well-founded objectives, which in turn determine the appropriate design, course, and outcome of the study. This article then aims to discuss in detail the various aspects of crafting research questions and hypotheses, with the goal of guiding researchers as they develop their own. Examples from the authors and peer-reviewed scientific articles in the healthcare field are provided to illustrate key points.

DEFINITIONS AND RELATIONSHIP OF RESEARCH QUESTIONS AND HYPOTHESES

A research question is what a study aims to answer after data analysis and interpretation. The answer is written in length in the discussion section of the paper. Thus, the research question gives a preview of the different parts and variables of the study meant to address the problem posed in the research question. 1 An excellent research question clarifies the research writing while facilitating understanding of the research topic, objective, scope, and limitations of the study. 5

On the other hand, a research hypothesis is an educated statement of an expected outcome. This statement is based on background research and current knowledge. 8 , 9 The research hypothesis makes a specific prediction about a new phenomenon 10 or a formal statement on the expected relationship between an independent variable and a dependent variable. 3 , 11 It provides a tentative answer to the research question to be tested or explored. 4

Hypotheses employ reasoning to predict a theory-based outcome. 10 These can also be developed from theories by focusing on components of theories that have not yet been observed. 10 The validity of hypotheses is often based on the testability of the prediction made in a reproducible experiment. 8

Conversely, hypotheses can also be rephrased as research questions. Several hypotheses based on existing theories and knowledge may be needed to answer a research question. Developing ethical research questions and hypotheses creates a research design that has logical relationships among variables. These relationships serve as a solid foundation for the conduct of the study. 4 , 11 Haphazardly constructed research questions can result in poorly formulated hypotheses and improper study designs, leading to unreliable results. Thus, the formulations of relevant research questions and verifiable hypotheses are crucial when beginning research. 12

CHARACTERISTICS OF GOOD RESEARCH QUESTIONS AND HYPOTHESES

Excellent research questions are specific and focused. These integrate collective data and observations to confirm or refute the subsequent hypotheses. Well-constructed hypotheses are based on previous reports and verify the research context. These are realistic, in-depth, sufficiently complex, and reproducible. More importantly, these hypotheses can be addressed and tested. 13

There are several characteristics of well-developed hypotheses. Good hypotheses are 1) empirically testable 7 , 10 , 11 , 13 ; 2) backed by preliminary evidence 9 ; 3) testable by ethical research 7 , 9 ; 4) based on original ideas 9 ; 5) have evidenced-based logical reasoning 10 ; and 6) can be predicted. 11 Good hypotheses can infer ethical and positive implications, indicating the presence of a relationship or effect relevant to the research theme. 7 , 11 These are initially developed from a general theory and branch into specific hypotheses by deductive reasoning. In the absence of a theory to base the hypotheses, inductive reasoning based on specific observations or findings form more general hypotheses. 10

TYPES OF RESEARCH QUESTIONS AND HYPOTHESES

Research questions and hypotheses are developed according to the type of research, which can be broadly classified into quantitative and qualitative research. We provide a summary of the types of research questions and hypotheses under quantitative and qualitative research categories in Table 1 .

Research questions in quantitative research

In quantitative research, research questions inquire about the relationships among variables being investigated and are usually framed at the start of the study. These are precise and typically linked to the subject population, dependent and independent variables, and research design. 1 Research questions may also attempt to describe the behavior of a population in relation to one or more variables, or describe the characteristics of variables to be measured ( descriptive research questions ). 1 , 5 , 14 These questions may also aim to discover differences between groups within the context of an outcome variable ( comparative research questions ), 1 , 5 , 14 or elucidate trends and interactions among variables ( relationship research questions ). 1 , 5 We provide examples of descriptive, comparative, and relationship research questions in quantitative research in Table 2 .

Hypotheses in quantitative research

In quantitative research, hypotheses predict the expected relationships among variables. 15 Relationships among variables that can be predicted include 1) between a single dependent variable and a single independent variable ( simple hypothesis ) or 2) between two or more independent and dependent variables ( complex hypothesis ). 4 , 11 Hypotheses may also specify the expected direction to be followed and imply an intellectual commitment to a particular outcome ( directional hypothesis ) 4 . On the other hand, hypotheses may not predict the exact direction and are used in the absence of a theory, or when findings contradict previous studies ( non-directional hypothesis ). 4 In addition, hypotheses can 1) define interdependency between variables ( associative hypothesis ), 4 2) propose an effect on the dependent variable from manipulation of the independent variable ( causal hypothesis ), 4 3) state a negative relationship between two variables ( null hypothesis ), 4 , 11 , 15 4) replace the working hypothesis if rejected ( alternative hypothesis ), 15 explain the relationship of phenomena to possibly generate a theory ( working hypothesis ), 11 5) involve quantifiable variables that can be tested statistically ( statistical hypothesis ), 11 6) or express a relationship whose interlinks can be verified logically ( logical hypothesis ). 11 We provide examples of simple, complex, directional, non-directional, associative, causal, null, alternative, working, statistical, and logical hypotheses in quantitative research, as well as the definition of quantitative hypothesis-testing research in Table 3 .

Research questions in qualitative research

Unlike research questions in quantitative research, research questions in qualitative research are usually continuously reviewed and reformulated. The central question and associated subquestions are stated more than the hypotheses. 15 The central question broadly explores a complex set of factors surrounding the central phenomenon, aiming to present the varied perspectives of participants. 15

There are varied goals for which qualitative research questions are developed. These questions can function in several ways, such as to 1) identify and describe existing conditions ( contextual research question s); 2) describe a phenomenon ( descriptive research questions ); 3) assess the effectiveness of existing methods, protocols, theories, or procedures ( evaluation research questions ); 4) examine a phenomenon or analyze the reasons or relationships between subjects or phenomena ( explanatory research questions ); or 5) focus on unknown aspects of a particular topic ( exploratory research questions ). 5 In addition, some qualitative research questions provide new ideas for the development of theories and actions ( generative research questions ) or advance specific ideologies of a position ( ideological research questions ). 1 Other qualitative research questions may build on a body of existing literature and become working guidelines ( ethnographic research questions ). Research questions may also be broadly stated without specific reference to the existing literature or a typology of questions ( phenomenological research questions ), may be directed towards generating a theory of some process ( grounded theory questions ), or may address a description of the case and the emerging themes ( qualitative case study questions ). 15 We provide examples of contextual, descriptive, evaluation, explanatory, exploratory, generative, ideological, ethnographic, phenomenological, grounded theory, and qualitative case study research questions in qualitative research in Table 4 , and the definition of qualitative hypothesis-generating research in Table 5 .

Qualitative studies usually pose at least one central research question and several subquestions starting with How or What . These research questions use exploratory verbs such as explore or describe . These also focus on one central phenomenon of interest, and may mention the participants and research site. 15

Hypotheses in qualitative research

Hypotheses in qualitative research are stated in the form of a clear statement concerning the problem to be investigated. Unlike in quantitative research where hypotheses are usually developed to be tested, qualitative research can lead to both hypothesis-testing and hypothesis-generating outcomes. 2 When studies require both quantitative and qualitative research questions, this suggests an integrative process between both research methods wherein a single mixed-methods research question can be developed. 1

FRAMEWORKS FOR DEVELOPING RESEARCH QUESTIONS AND HYPOTHESES

Research questions followed by hypotheses should be developed before the start of the study. 1 , 12 , 14 It is crucial to develop feasible research questions on a topic that is interesting to both the researcher and the scientific community. This can be achieved by a meticulous review of previous and current studies to establish a novel topic. Specific areas are subsequently focused on to generate ethical research questions. The relevance of the research questions is evaluated in terms of clarity of the resulting data, specificity of the methodology, objectivity of the outcome, depth of the research, and impact of the study. 1 , 5 These aspects constitute the FINER criteria (i.e., Feasible, Interesting, Novel, Ethical, and Relevant). 1 Clarity and effectiveness are achieved if research questions meet the FINER criteria. In addition to the FINER criteria, Ratan et al. described focus, complexity, novelty, feasibility, and measurability for evaluating the effectiveness of research questions. 14

The PICOT and PEO frameworks are also used when developing research questions. 1 The following elements are addressed in these frameworks, PICOT: P-population/patients/problem, I-intervention or indicator being studied, C-comparison group, O-outcome of interest, and T-timeframe of the study; PEO: P-population being studied, E-exposure to preexisting conditions, and O-outcome of interest. 1 Research questions are also considered good if these meet the “FINERMAPS” framework: Feasible, Interesting, Novel, Ethical, Relevant, Manageable, Appropriate, Potential value/publishable, and Systematic. 14

As we indicated earlier, research questions and hypotheses that are not carefully formulated result in unethical studies or poor outcomes. To illustrate this, we provide some examples of ambiguous research question and hypotheses that result in unclear and weak research objectives in quantitative research ( Table 6 ) 16 and qualitative research ( Table 7 ) 17 , and how to transform these ambiguous research question(s) and hypothesis(es) into clear and good statements.

a These statements were composed for comparison and illustrative purposes only.

b These statements are direct quotes from Higashihara and Horiuchi. 16

a This statement is a direct quote from Shimoda et al. 17

The other statements were composed for comparison and illustrative purposes only.

CONSTRUCTING RESEARCH QUESTIONS AND HYPOTHESES

To construct effective research questions and hypotheses, it is very important to 1) clarify the background and 2) identify the research problem at the outset of the research, within a specific timeframe. 9 Then, 3) review or conduct preliminary research to collect all available knowledge about the possible research questions by studying theories and previous studies. 18 Afterwards, 4) construct research questions to investigate the research problem. Identify variables to be accessed from the research questions 4 and make operational definitions of constructs from the research problem and questions. Thereafter, 5) construct specific deductive or inductive predictions in the form of hypotheses. 4 Finally, 6) state the study aims . This general flow for constructing effective research questions and hypotheses prior to conducting research is shown in Fig. 1 .

Research questions are used more frequently in qualitative research than objectives or hypotheses. 3 These questions seek to discover, understand, explore or describe experiences by asking “What” or “How.” The questions are open-ended to elicit a description rather than to relate variables or compare groups. The questions are continually reviewed, reformulated, and changed during the qualitative study. 3 Research questions are also used more frequently in survey projects than hypotheses in experiments in quantitative research to compare variables and their relationships.

Hypotheses are constructed based on the variables identified and as an if-then statement, following the template, ‘If a specific action is taken, then a certain outcome is expected.’ At this stage, some ideas regarding expectations from the research to be conducted must be drawn. 18 Then, the variables to be manipulated (independent) and influenced (dependent) are defined. 4 Thereafter, the hypothesis is stated and refined, and reproducible data tailored to the hypothesis are identified, collected, and analyzed. 4 The hypotheses must be testable and specific, 18 and should describe the variables and their relationships, the specific group being studied, and the predicted research outcome. 18 Hypotheses construction involves a testable proposition to be deduced from theory, and independent and dependent variables to be separated and measured separately. 3 Therefore, good hypotheses must be based on good research questions constructed at the start of a study or trial. 12

In summary, research questions are constructed after establishing the background of the study. Hypotheses are then developed based on the research questions. Thus, it is crucial to have excellent research questions to generate superior hypotheses. In turn, these would determine the research objectives and the design of the study, and ultimately, the outcome of the research. 12 Algorithms for building research questions and hypotheses are shown in Fig. 2 for quantitative research and in Fig. 3 for qualitative research.

EXAMPLES OF RESEARCH QUESTIONS FROM PUBLISHED ARTICLES

• EXAMPLE 1. Descriptive research question (quantitative research)
• - Presents research variables to be assessed (distinct phenotypes and subphenotypes)
• “BACKGROUND: Since COVID-19 was identified, its clinical and biological heterogeneity has been recognized. Identifying COVID-19 phenotypes might help guide basic, clinical, and translational research efforts.
• RESEARCH QUESTION: Does the clinical spectrum of patients with COVID-19 contain distinct phenotypes and subphenotypes? ” 19
• EXAMPLE 2. Relationship research question (quantitative research)
• - Shows interactions between dependent variable (static postural control) and independent variable (peripheral visual field loss)
• “Background: Integration of visual, vestibular, and proprioceptive sensations contributes to postural control. People with peripheral visual field loss have serious postural instability. However, the directional specificity of postural stability and sensory reweighting caused by gradual peripheral visual field loss remain unclear.
• Research question: What are the effects of peripheral visual field loss on static postural control ?” 20
• EXAMPLE 3. Comparative research question (quantitative research)
• - Clarifies the difference among groups with an outcome variable (patients enrolled in COMPERA with moderate PH or severe PH in COPD) and another group without the outcome variable (patients with idiopathic pulmonary arterial hypertension (IPAH))
• “BACKGROUND: Pulmonary hypertension (PH) in COPD is a poorly investigated clinical condition.
• RESEARCH QUESTION: Which factors determine the outcome of PH in COPD?
• STUDY DESIGN AND METHODS: We analyzed the characteristics and outcome of patients enrolled in the Comparative, Prospective Registry of Newly Initiated Therapies for Pulmonary Hypertension (COMPERA) with moderate or severe PH in COPD as defined during the 6th PH World Symposium who received medical therapy for PH and compared them with patients with idiopathic pulmonary arterial hypertension (IPAH) .” 21
• EXAMPLE 4. Exploratory research question (qualitative research)
• - Explores areas that have not been fully investigated (perspectives of families and children who receive care in clinic-based child obesity treatment) to have a deeper understanding of the research problem
• “Problem: Interventions for children with obesity lead to only modest improvements in BMI and long-term outcomes, and data are limited on the perspectives of families of children with obesity in clinic-based treatment. This scoping review seeks to answer the question: What is known about the perspectives of families and children who receive care in clinic-based child obesity treatment? This review aims to explore the scope of perspectives reported by families of children with obesity who have received individualized outpatient clinic-based obesity treatment.” 22
• EXAMPLE 5. Relationship research question (quantitative research)
• - Defines interactions between dependent variable (use of ankle strategies) and independent variable (changes in muscle tone)
• “Background: To maintain an upright standing posture against external disturbances, the human body mainly employs two types of postural control strategies: “ankle strategy” and “hip strategy.” While it has been reported that the magnitude of the disturbance alters the use of postural control strategies, it has not been elucidated how the level of muscle tone, one of the crucial parameters of bodily function, determines the use of each strategy. We have previously confirmed using forward dynamics simulations of human musculoskeletal models that an increased muscle tone promotes the use of ankle strategies. The objective of the present study was to experimentally evaluate a hypothesis: an increased muscle tone promotes the use of ankle strategies. Research question: Do changes in the muscle tone affect the use of ankle strategies ?” 23

EXAMPLES OF HYPOTHESES IN PUBLISHED ARTICLES

• EXAMPLE 1. Working hypothesis (quantitative research)
• - A hypothesis that is initially accepted for further research to produce a feasible theory
• “As fever may have benefit in shortening the duration of viral illness, it is plausible to hypothesize that the antipyretic efficacy of ibuprofen may be hindering the benefits of a fever response when taken during the early stages of COVID-19 illness .” 24
• “In conclusion, it is plausible to hypothesize that the antipyretic efficacy of ibuprofen may be hindering the benefits of a fever response . The difference in perceived safety of these agents in COVID-19 illness could be related to the more potent efficacy to reduce fever with ibuprofen compared to acetaminophen. Compelling data on the benefit of fever warrant further research and review to determine when to treat or withhold ibuprofen for early stage fever for COVID-19 and other related viral illnesses .” 24
• EXAMPLE 2. Exploratory hypothesis (qualitative research)
• - Explores particular areas deeper to clarify subjective experience and develop a formal hypothesis potentially testable in a future quantitative approach
• “We hypothesized that when thinking about a past experience of help-seeking, a self distancing prompt would cause increased help-seeking intentions and more favorable help-seeking outcome expectations .” 25
• “Conclusion
• Although a priori hypotheses were not supported, further research is warranted as results indicate the potential for using self-distancing approaches to increasing help-seeking among some people with depressive symptomatology.” 25
• EXAMPLE 3. Hypothesis-generating research to establish a framework for hypothesis testing (qualitative research)
• “We hypothesize that compassionate care is beneficial for patients (better outcomes), healthcare systems and payers (lower costs), and healthcare providers (lower burnout). ” 26
• Compassionomics is the branch of knowledge and scientific study of the effects of compassionate healthcare. Our main hypotheses are that compassionate healthcare is beneficial for (1) patients, by improving clinical outcomes, (2) healthcare systems and payers, by supporting financial sustainability, and (3) HCPs, by lowering burnout and promoting resilience and well-being. The purpose of this paper is to establish a scientific framework for testing the hypotheses above . If these hypotheses are confirmed through rigorous research, compassionomics will belong in the science of evidence-based medicine, with major implications for all healthcare domains.” 26
• EXAMPLE 4. Statistical hypothesis (quantitative research)
• - An assumption is made about the relationship among several population characteristics ( gender differences in sociodemographic and clinical characteristics of adults with ADHD ). Validity is tested by statistical experiment or analysis ( chi-square test, Students t-test, and logistic regression analysis)
• “Our research investigated gender differences in sociodemographic and clinical characteristics of adults with ADHD in a Japanese clinical sample. Due to unique Japanese cultural ideals and expectations of women's behavior that are in opposition to ADHD symptoms, we hypothesized that women with ADHD experience more difficulties and present more dysfunctions than men . We tested the following hypotheses: first, women with ADHD have more comorbidities than men with ADHD; second, women with ADHD experience more social hardships than men, such as having less full-time employment and being more likely to be divorced.” 27
• “Statistical Analysis
• ( text omitted ) Between-gender comparisons were made using the chi-squared test for categorical variables and Students t-test for continuous variables…( text omitted ). A logistic regression analysis was performed for employment status, marital status, and comorbidity to evaluate the independent effects of gender on these dependent variables.” 27

EXAMPLES OF HYPOTHESIS AS WRITTEN IN PUBLISHED ARTICLES IN RELATION TO OTHER PARTS

• EXAMPLE 1. Background, hypotheses, and aims are provided
• “Pregnant women need skilled care during pregnancy and childbirth, but that skilled care is often delayed in some countries …( text omitted ). The focused antenatal care (FANC) model of WHO recommends that nurses provide information or counseling to all pregnant women …( text omitted ). Job aids are visual support materials that provide the right kind of information using graphics and words in a simple and yet effective manner. When nurses are not highly trained or have many work details to attend to, these job aids can serve as a content reminder for the nurses and can be used for educating their patients (Jennings, Yebadokpo, Affo, & Agbogbe, 2010) ( text omitted ). Importantly, additional evidence is needed to confirm how job aids can further improve the quality of ANC counseling by health workers in maternal care …( text omitted )” 28
• “ This has led us to hypothesize that the quality of ANC counseling would be better if supported by job aids. Consequently, a better quality of ANC counseling is expected to produce higher levels of awareness concerning the danger signs of pregnancy and a more favorable impression of the caring behavior of nurses .” 28
• “This study aimed to examine the differences in the responses of pregnant women to a job aid-supported intervention during ANC visit in terms of 1) their understanding of the danger signs of pregnancy and 2) their impression of the caring behaviors of nurses to pregnant women in rural Tanzania.” 28
• EXAMPLE 2. Background, hypotheses, and aims are provided
• “We conducted a two-arm randomized controlled trial (RCT) to evaluate and compare changes in salivary cortisol and oxytocin levels of first-time pregnant women between experimental and control groups. The women in the experimental group touched and held an infant for 30 min (experimental intervention protocol), whereas those in the control group watched a DVD movie of an infant (control intervention protocol). The primary outcome was salivary cortisol level and the secondary outcome was salivary oxytocin level.” 29
• “ We hypothesize that at 30 min after touching and holding an infant, the salivary cortisol level will significantly decrease and the salivary oxytocin level will increase in the experimental group compared with the control group .” 29
• EXAMPLE 3. Background, aim, and hypothesis are provided
• “In countries where the maternal mortality ratio remains high, antenatal education to increase Birth Preparedness and Complication Readiness (BPCR) is considered one of the top priorities [1]. BPCR includes birth plans during the antenatal period, such as the birthplace, birth attendant, transportation, health facility for complications, expenses, and birth materials, as well as family coordination to achieve such birth plans. In Tanzania, although increasing, only about half of all pregnant women attend an antenatal clinic more than four times [4]. Moreover, the information provided during antenatal care (ANC) is insufficient. In the resource-poor settings, antenatal group education is a potential approach because of the limited time for individual counseling at antenatal clinics.” 30
• “This study aimed to evaluate an antenatal group education program among pregnant women and their families with respect to birth-preparedness and maternal and infant outcomes in rural villages of Tanzania.” 30
• “ The study hypothesis was if Tanzanian pregnant women and their families received a family-oriented antenatal group education, they would (1) have a higher level of BPCR, (2) attend antenatal clinic four or more times, (3) give birth in a health facility, (4) have less complications of women at birth, and (5) have less complications and deaths of infants than those who did not receive the education .” 30

Research questions and hypotheses are crucial components to any type of research, whether quantitative or qualitative. These questions should be developed at the very beginning of the study. Excellent research questions lead to superior hypotheses, which, like a compass, set the direction of research, and can often determine the successful conduct of the study. Many research studies have floundered because the development of research questions and subsequent hypotheses was not given the thought and meticulous attention needed. The development of research questions and hypotheses is an iterative process based on extensive knowledge of the literature and insightful grasp of the knowledge gap. Focused, concise, and specific research questions provide a strong foundation for constructing hypotheses which serve as formal predictions about the research outcomes. Research questions and hypotheses are crucial elements of research that should not be overlooked. They should be carefully thought of and constructed when planning research. This avoids unethical studies and poor outcomes by defining well-founded objectives that determine the design, course, and outcome of the study.

Disclosure: The authors have no potential conflicts of interest to disclose.

Author Contributions:

• Conceptualization: Barroga E, Matanguihan GJ.
• Methodology: Barroga E, Matanguihan GJ.
• Writing - original draft: Barroga E, Matanguihan GJ.
• Writing - review & editing: Barroga E, Matanguihan GJ.

Cultural Relativity and Acceptance of Embryonic Stem Cell Research

Article sidebar.

Main Article Content

There is a debate about the ethical implications of using human embryos in stem cell research, which can be influenced by cultural, moral, and social values. This paper argues for an adaptable framework to accommodate diverse cultural and religious perspectives. By using an adaptive ethics model, research protections can reflect various populations and foster growth in stem cell research possibilities.

INTRODUCTION

Stem cell research combines biology, medicine, and technology, promising to alter health care and the understanding of human development. Yet, ethical contention exists because of individuals’ perceptions of using human embryos based on their various cultural, moral, and social values. While these disagreements concerning policy, use, and general acceptance have prompted the development of an international ethics policy, such a uniform approach can overlook the nuanced ethical landscapes between cultures. With diverse viewpoints in public health, a single global policy, especially one reflecting Western ethics or the ethics prevalent in high-income countries, is impractical. This paper argues for a culturally sensitive, adaptable framework for the use of embryonic stem cells. Stem cell policy should accommodate varying ethical viewpoints and promote an effective global dialogue. With an extension of an ethics model that can adapt to various cultures, we recommend localized guidelines that reflect the moral views of the people those guidelines serve.

Stem cells, characterized by their unique ability to differentiate into various cell types, enable the repair or replacement of damaged tissues. Two primary types of stem cells are somatic stem cells (adult stem cells) and embryonic stem cells. Adult stem cells exist in developed tissues and maintain the body’s repair processes. [1] Embryonic stem cells (ESC) are remarkably pluripotent or versatile, making them valuable in research. [2] However, the use of ESCs has sparked ethics debates. Considering the potential of embryonic stem cells, research guidelines are essential. The International Society for Stem Cell Research (ISSCR) provides international stem cell research guidelines. They call for “public conversations touching on the scientific significance as well as the societal and ethical issues raised by ESC research.” [3] The ISSCR also publishes updates about culturing human embryos 14 days post fertilization, suggesting local policies and regulations should continue to evolve as ESC research develops. [4]  Like the ISSCR, which calls for local law and policy to adapt to developing stem cell research given cultural acceptance, this paper highlights the importance of local social factors such as religion and culture.

I.     Global Cultural Perspective of Embryonic Stem Cells

Views on ESCs vary throughout the world. Some countries readily embrace stem cell research and therapies, while others have stricter regulations due to ethical concerns surrounding embryonic stem cells and when an embryo becomes entitled to moral consideration. The philosophical issue of when the “someone” begins to be a human after fertilization, in the morally relevant sense, [5] impacts when an embryo becomes not just worthy of protection but morally entitled to it. The process of creating embryonic stem cell lines involves the destruction of the embryos for research. [6] Consequently, global engagement in ESC research depends on social-cultural acceptability.

a.     US and Rights-Based Cultures

In the United States, attitudes toward stem cell therapies are diverse. The ethics and social approaches, which value individualism, [7] trigger debates regarding the destruction of human embryos, creating a complex regulatory environment. For example, the 1996 Dickey-Wicker Amendment prohibited federal funding for the creation of embryos for research and the destruction of embryos for “more than allowed for research on fetuses in utero.” [8] Following suit, in 2001, the Bush Administration heavily restricted stem cell lines for research. However, the Stem Cell Research Enhancement Act of 2005 was proposed to help develop ESC research but was ultimately vetoed. [9] Under the Obama administration, in 2009, an executive order lifted restrictions allowing for more development in this field. [10] The flux of research capacity and funding parallels the different cultural perceptions of human dignity of the embryo and how it is socially presented within the country’s research culture. [11]

b.     Ubuntu and Collective Cultures

African bioethics differs from Western individualism because of the different traditions and values. African traditions, as described by individuals from South Africa and supported by some studies in other African countries, including Ghana and Kenya, follow the African moral philosophies of Ubuntu or Botho and Ukama , which “advocates for a form of wholeness that comes through one’s relationship and connectedness with other people in the society,” [12] making autonomy a socially collective concept. In this context, for the community to act autonomously, individuals would come together to decide what is best for the collective. Thus, stem cell research would require examining the value of the research to society as a whole and the use of the embryos as a collective societal resource. If society views the source as part of the collective whole, and opposes using stem cells, compromising the cultural values to pursue research may cause social detachment and stunt research growth. [13] Based on local culture and moral philosophy, the permissibility of stem cell research depends on how embryo, stem cell, and cell line therapies relate to the community as a whole. Ubuntu is the expression of humanness, with the person’s identity drawn from the “’I am because we are’” value. [14] The decision in a collectivistic culture becomes one born of cultural context, and individual decisions give deference to others in the society.

Consent differs in cultures where thought and moral philosophy are based on a collective paradigm. So, applying Western bioethical concepts is unrealistic. For one, Africa is a diverse continent with many countries with different belief systems, access to health care, and reliance on traditional or Western medicines. Where traditional medicine is the primary treatment, the “’restrictive focus on biomedically-related bioethics’” [is] problematic in African contexts because it neglects bioethical issues raised by traditional systems.” [15] No single approach applies in all areas or contexts. Rather than evaluating the permissibility of ESC research according to Western concepts such as the four principles approach, different ethics approaches should prevail.

Another consideration is the socio-economic standing of countries. In parts of South Africa, researchers have not focused heavily on contributing to the stem cell discourse, either because it is not considered health care or a health science priority or because resources are unavailable. [16] Each country’s priorities differ given different social, political, and economic factors. In South Africa, for instance, areas such as maternal mortality, non-communicable diseases, telemedicine, and the strength of health systems need improvement and require more focus [17] Stem cell research could benefit the population, but it also could divert resources from basic medical care. Researchers in South Africa adhere to the National Health Act and Medicines Control Act in South Africa and international guidelines; however, the Act is not strictly enforced, and there is no clear legislation for research conduct or ethical guidelines. [18]

Some parts of Africa condemn stem cell research. For example, 98.2 percent of the Tunisian population is Muslim. [19] Tunisia does not permit stem cell research because of moral conflict with a Fatwa. Religion heavily saturates the regulation and direction of research. [20] Stem cell use became permissible for reproductive purposes only recently, with tight restrictions preventing cells from being used in any research other than procedures concerning ART/IVF.  Their use is conditioned on consent, and available only to married couples. [21] The community's receptiveness to stem cell research depends on including communitarian African ethics.

c.     Asia

Some Asian countries also have a collective model of ethics and decision making. [22] In China, the ethics model promotes a sincere respect for life or human dignity, [23] based on protective medicine. This model, influenced by Traditional Chinese Medicine (TCM), [24] recognizes Qi as the vital energy delivered via the meridians of the body; it connects illness to body systems, the body’s entire constitution, and the universe for a holistic bond of nature, health, and quality of life. [25] Following a protective ethics model, and traditional customs of wholeness, investment in stem cell research is heavily desired for its applications in regenerative therapies, disease modeling, and protective medicines. In a survey of medical students and healthcare practitioners, 30.8 percent considered stem cell research morally unacceptable while 63.5 percent accepted medical research using human embryonic stem cells. Of these individuals, 89.9 percent supported increased funding for stem cell research. [26] The scientific community might not reflect the overall population. From 1997 to 2019, China spent a total of $576 million (USD) on stem cell research at 8,050 stem cell programs, increased published presence from 0.6 percent to 14.01 percent of total global stem cell publications as of 2014, and made significant strides in cell-based therapies for various medical conditions. [27] However, while China has made substantial investments in stem cell research and achieved notable progress in clinical applications, concerns linger regarding ethical oversight and transparency. [28] For example, the China Biosecurity Law, promoted by the National Health Commission and China Hospital Association, attempted to mitigate risks by introducing an institutional review board (IRB) in the regulatory bodies. 5800 IRBs registered with the Chinese Clinical Trial Registry since 2021. [29] However, issues still need to be addressed in implementing effective IRB review and approval procedures.

The substantial government funding and focus on scientific advancement have sometimes overshadowed considerations of regional cultures, ethnic minorities, and individual perspectives, particularly evident during the one-child policy era. As government policy adapts to promote public stability, such as the change from the one-child to the two-child policy, [30] research ethics should also adapt to ensure respect for the values of its represented peoples.

Japan is also relatively supportive of stem cell research and therapies. Japan has a more transparent regulatory framework, allowing for faster approval of regenerative medicine products, which has led to several advanced clinical trials and therapies. [31] South Korea is also actively engaged in stem cell research and has a history of breakthroughs in cloning and embryonic stem cells. [32] However, the field is controversial, and there are issues of scientific integrity. For example, the Korean FDA fast-tracked products for approval, [33] and in another instance, the oocyte source was unclear and possibly violated ethical standards. [34] Trust is important in research, as it builds collaborative foundations between colleagues, trial participant comfort, open-mindedness for complicated and sensitive discussions, and supports regulatory procedures for stakeholders. There is a need to respect the culture’s interest, engagement, and for research and clinical trials to be transparent and have ethical oversight to promote global research discourse and trust.

d.     Middle East

Countries in the Middle East have varying degrees of acceptance of or restrictions to policies related to using embryonic stem cells due to cultural and religious influences. Saudi Arabia has made significant contributions to stem cell research, and conducts research based on international guidelines for ethical conduct and under strict adherence to guidelines in accordance with Islamic principles. Specifically, the Saudi government and people require ESC research to adhere to Sharia law. In addition to umbilical and placental stem cells, [35] Saudi Arabia permits the use of embryonic stem cells as long as they come from miscarriages, therapeutic abortions permissible by Sharia law, or are left over from in vitro fertilization and donated to research. [36] Laws and ethical guidelines for stem cell research allow the development of research institutions such as the King Abdullah International Medical Research Center, which has a cord blood bank and a stem cell registry with nearly 10,000 donors. [37] Such volume and acceptance are due to the ethical ‘permissibility’ of the donor sources, which do not conflict with religious pillars. However, some researchers err on the side of caution, choosing not to use embryos or fetal tissue as they feel it is unethical to do so. [38]

Jordan has a positive research ethics culture. [39] However, there is a significant issue of lack of trust in researchers, with 45.23 percent (38.66 percent agreeing and 6.57 percent strongly agreeing) of Jordanians holding a low level of trust in researchers, compared to 81.34 percent of Jordanians agreeing that they feel safe to participate in a research trial. [40] Safety testifies to the feeling of confidence that adequate measures are in place to protect participants from harm, whereas trust in researchers could represent the confidence in researchers to act in the participants’ best interests, adhere to ethical guidelines, provide accurate information, and respect participants’ rights and dignity. One method to improve trust would be to address communication issues relevant to ESC. Legislation surrounding stem cell research has adopted specific language, especially concerning clarification “between ‘stem cells’ and ‘embryonic stem cells’” in translation. [41] Furthermore, legislation “mandates the creation of a national committee… laying out specific regulations for stem-cell banking in accordance with international standards.” [42] This broad regulation opens the door for future global engagement and maintains transparency. However, these regulations may also constrain the influence of research direction, pace, and accessibility of research outcomes.

e.     Europe

In the European Union (EU), ethics is also principle-based, but the principles of autonomy, dignity, integrity, and vulnerability are interconnected. [43] As such, the opportunity for cohesion and concessions between individuals’ thoughts and ideals allows for a more adaptable ethics model due to the flexible principles that relate to the human experience The EU has put forth a framework in its Convention for the Protection of Human Rights and Dignity of the Human Being allowing member states to take different approaches. Each European state applies these principles to its specific conventions, leading to or reflecting different acceptance levels of stem cell research. [44]

For example, in Germany, Lebenzusammenhang , or the coherence of life, references integrity in the unity of human culture. Namely, the personal sphere “should not be subject to external intervention.” [45]  Stem cell interventions could affect this concept of bodily completeness, leading to heavy restrictions. Under the Grundgesetz, human dignity and the right to life with physical integrity are paramount. [46] The Embryo Protection Act of 1991 made producing cell lines illegal. Cell lines can be imported if approved by the Central Ethics Commission for Stem Cell Research only if they were derived before May 2007. [47] Stem cell research respects the integrity of life for the embryo with heavy specifications and intense oversight. This is vastly different in Finland, where the regulatory bodies find research more permissible in IVF excess, but only up to 14 days after fertilization. [48] Spain’s approach differs still, with a comprehensive regulatory framework. [49] Thus, research regulation can be culture-specific due to variations in applied principles. Diverse cultures call for various approaches to ethical permissibility. [50] Only an adaptive-deliberative model can address the cultural constructions of self and achieve positive, culturally sensitive stem cell research practices. [51]

II.     Religious Perspectives on ESC

Embryonic stem cell sources are the main consideration within religious contexts. While individuals may not regard their own religious texts as authoritative or factual, religion can shape their foundations or perspectives.

The Qur'an states:

“And indeed We created man from a quintessence of clay. Then We placed within him a small quantity of nutfa (sperm to fertilize) in a safe place. Then We have fashioned the nutfa into an ‘alaqa (clinging clot or cell cluster), then We developed the ‘alaqa into mudgha (a lump of flesh), and We made mudgha into bones, and clothed the bones with flesh, then We brought it into being as a new creation. So Blessed is Allah, the Best of Creators.” [52]

Many scholars of Islam estimate the time of soul installment, marked by the angel breathing in the soul to bring the individual into creation, as 120 days from conception. [53] Personhood begins at this point, and the value of life would prohibit research or experimentation that could harm the individual. If the fetus is more than 120 days old, the time ensoulment is interpreted to occur according to Islamic law, abortion is no longer permissible. [54] There are a few opposing opinions about early embryos in Islamic traditions. According to some Islamic theologians, there is no ensoulment of the early embryo, which is the source of stem cells for ESC research. [55]

In Buddhism, the stance on stem cell research is not settled. The main tenets, the prohibition against harming or destroying others (ahimsa) and the pursuit of knowledge (prajña) and compassion (karuna), leave Buddhist scholars and communities divided. [56] Some scholars argue stem cell research is in accordance with the Buddhist tenet of seeking knowledge and ending human suffering. Others feel it violates the principle of not harming others. Finding the balance between these two points relies on the karmic burden of Buddhist morality. In trying to prevent ahimsa towards the embryo, Buddhist scholars suggest that to comply with Buddhist tenets, research cannot be done as the embryo has personhood at the moment of conception and would reincarnate immediately, harming the individual's ability to build their karmic burden. [57] On the other hand, the Bodhisattvas, those considered to be on the path to enlightenment or Nirvana, have given organs and flesh to others to help alleviate grieving and to benefit all. [58] Acceptance varies on applied beliefs and interpretations.

Catholicism does not support embryonic stem cell research, as it entails creation or destruction of human embryos. This destruction conflicts with the belief in the sanctity of life. For example, in the Old Testament, Genesis describes humanity as being created in God’s image and multiplying on the Earth, referencing the sacred rights to human conception and the purpose of development and life. In the Ten Commandments, the tenet that one should not kill has numerous interpretations where killing could mean murder or shedding of the sanctity of life, demonstrating the high value of human personhood. In other books, the theological conception of when life begins is interpreted as in utero, [59] highlighting the inviolability of life and its formation in vivo to make a religious point for accepting such research as relatively limited, if at all. [60] The Vatican has released ethical directives to help apply a theological basis to modern-day conflicts. The Magisterium of the Church states that “unless there is a moral certainty of not causing harm,” experimentation on fetuses, fertilized cells, stem cells, or embryos constitutes a crime. [61] Such procedures would not respect the human person who exists at these stages, according to Catholicism. Damages to the embryo are considered gravely immoral and illicit. [62] Although the Catholic Church officially opposes abortion, surveys demonstrate that many Catholic people hold pro-choice views, whether due to the context of conception, stage of pregnancy, threat to the mother’s life, or for other reasons, demonstrating that practicing members can also accept some but not all tenets. [63]

Some major Jewish denominations, such as the Reform, Conservative, and Reconstructionist movements, are open to supporting ESC use or research as long as it is for saving a life. [64] Within Judaism, the Talmud, or study, gives personhood to the child at birth and emphasizes that life does not begin at conception: [65]

“If she is found pregnant, until the fortieth day it is mere fluid,” [66]

Whereas most religions prioritize the status of human embryos, the Halakah (Jewish religious law) states that to save one life, most other religious laws can be ignored because it is in pursuit of preservation. [67] Stem cell research is accepted due to application of these religious laws.

We recognize that all religions contain subsets and sects. The variety of environmental and cultural differences within religious groups requires further analysis to respect the flexibility of religious thoughts and practices. We make no presumptions that all cultures require notions of autonomy or morality as under the common morality theory , which asserts a set of universal moral norms that all individuals share provides moral reasoning and guides ethical decisions. [68] We only wish to show that the interaction with morality varies between cultures and countries.

III.     A Flexible Ethical Approach

The plurality of different moral approaches described above demonstrates that there can be no universally acceptable uniform law for ESC on a global scale. Instead of developing one standard, flexible ethical applications must be continued. We recommend local guidelines that incorporate important cultural and ethical priorities.

While the Declaration of Helsinki is more relevant to people in clinical trials receiving ESC products, in keeping with the tradition of protections for research subjects, consent of the donor is an ethical requirement for ESC donation in many jurisdictions including the US, Canada, and Europe. [69] The Declaration of Helsinki provides a reference point for regulatory standards and could potentially be used as a universal baseline for obtaining consent prior to gamete or embryo donation.

For instance, in Columbia University’s egg donor program for stem cell research, donors followed standard screening protocols and “underwent counseling sessions that included information as to the purpose of oocyte donation for research, what the oocytes would be used for, the risks and benefits of donation, and process of oocyte stimulation” to ensure transparency for consent. [70] The program helped advance stem cell research and provided clear and safe research methods with paid participants. Though paid participation or covering costs of incidental expenses may not be socially acceptable in every culture or context, [71] and creating embryos for ESC research is illegal in many jurisdictions, Columbia’s program was effective because of the clear and honest communications with donors, IRBs, and related stakeholders.  This example demonstrates that cultural acceptance of scientific research and of the idea that an egg or embryo does not have personhood is likely behind societal acceptance of donating eggs for ESC research. As noted, many countries do not permit the creation of embryos for research.

Proper communication and education regarding the process and purpose of stem cell research may bolster comprehension and garner more acceptance. “Given the sensitive subject material, a complete consent process can support voluntary participation through trust, understanding, and ethical norms from the cultures and morals participants value. This can be hard for researchers entering countries of different socioeconomic stability, with different languages and different societal values. [72]

An adequate moral foundation in medical ethics is derived from the cultural and religious basis that informs knowledge and actions. [73] Understanding local cultural and religious values and their impact on research could help researchers develop humility and promote inclusion.

IV.     Concerns

Some may argue that if researchers all adhere to one ethics standard, protection will be satisfied across all borders, and the global public will trust researchers. However, defining what needs to be protected and how to define such research standards is very specific to the people to which standards are applied. We suggest that applying one uniform guide cannot accurately protect each individual because we all possess our own perceptions and interpretations of social values. [74] Therefore, the issue of not adjusting to the moral pluralism between peoples in applying one standard of ethics can be resolved by building out ethics models that can be adapted to different cultures and religions.

Other concerns include medical tourism, which may promote health inequities. [75] Some countries may develop and approve products derived from ESC research before others, compromising research ethics or drug approval processes. There are also concerns about the sale of unauthorized stem cell treatments, for example, those without FDA approval in the United States. Countries with robust research infrastructures may be tempted to attract medical tourists, and some customers will have false hopes based on aggressive publicity of unproven treatments. [76]

For example, in China, stem cell clinics can market to foreign clients who are not protected under the regulatory regimes. Companies employ a marketing strategy of “ethically friendly” therapies. Specifically, in the case of Beike, China’s leading stem cell tourism company and sprouting network, ethical oversight of administrators or health bureaus at one site has “the unintended consequence of shifting questionable activities to another node in Beike's diffuse network.” [77] In contrast, Jordan is aware of stem cell research’s potential abuse and its own status as a “health-care hub.” Jordan’s expanded regulations include preserving the interests of individuals in clinical trials and banning private companies from ESC research to preserve transparency and the integrity of research practices. [78]

The social priorities of the community are also a concern. The ISSCR explicitly states that guidelines “should be periodically revised to accommodate scientific advances, new challenges, and evolving social priorities.” [79] The adaptable ethics model extends this consideration further by addressing whether research is warranted given the varying degrees of socioeconomic conditions, political stability, and healthcare accessibilities and limitations. An ethical approach would require discussion about resource allocation and appropriate distribution of funds. [80]

While some religions emphasize the sanctity of life from conception, which may lead to public opposition to ESC research, others encourage ESC research due to its potential for healing and alleviating human pain. Many countries have special regulations that balance local views on embryonic personhood, the benefits of research as individual or societal goods, and the protection of human research subjects. To foster understanding and constructive dialogue, global policy frameworks should prioritize the protection of universal human rights, transparency, and informed consent. In addition to these foundational global policies, we recommend tailoring local guidelines to reflect the diverse cultural and religious perspectives of the populations they govern. Ethics models should be adapted to local populations to effectively establish research protections, growth, and possibilities of stem cell research.

For example, in countries with strong beliefs in the moral sanctity of embryos or heavy religious restrictions, an adaptive model can allow for discussion instead of immediate rejection. In countries with limited individual rights and voice in science policy, an adaptive model ensures cultural, moral, and religious views are taken into consideration, thereby building social inclusion. While this ethical consideration by the government may not give a complete voice to every individual, it will help balance policies and maintain the diverse perspectives of those it affects. Embracing an adaptive ethics model of ESC research promotes open-minded dialogue and respect for the importance of human belief and tradition. By actively engaging with cultural and religious values, researchers can better handle disagreements and promote ethical research practices that benefit each society.

This brief exploration of the religious and cultural differences that impact ESC research reveals the nuances of relative ethics and highlights a need for local policymakers to apply a more intense adaptive model.

[1] Poliwoda, S., Noor, N., Downs, E., Schaaf, A., Cantwell, A., Ganti, L., Kaye, A. D., Mosel, L. I., Carroll, C. B., Viswanath, O., & Urits, I. (2022). Stem cells: a comprehensive review of origins and emerging clinical roles in medical practice.  Orthopedic reviews ,  14 (3), 37498. https://doi.org/10.52965/001c.37498

[2] Poliwoda, S., Noor, N., Downs, E., Schaaf, A., Cantwell, A., Ganti, L., Kaye, A. D., Mosel, L. I., Carroll, C. B., Viswanath, O., & Urits, I. (2022). Stem cells: a comprehensive review of origins and emerging clinical roles in medical practice.  Orthopedic reviews ,  14 (3), 37498. https://doi.org/10.52965/001c.37498

[3] International Society for Stem Cell Research. (2023). Laboratory-based human embryonic stem cell research, embryo research, and related research activities . International Society for Stem Cell Research. https://www.isscr.org/guidelines/blog-post-title-one-ed2td-6fcdk ; Kimmelman, J., Hyun, I., Benvenisty, N.  et al.  Policy: Global standards for stem-cell research.  Nature   533 , 311–313 (2016). https://doi.org/10.1038/533311a

[4] International Society for Stem Cell Research. (2023). Laboratory-based human embryonic stem cell research, embryo research, and related research activities . International Society for Stem Cell Research. https://www.isscr.org/guidelines/blog-post-title-one-ed2td-6fcdk

[5] Concerning the moral philosophies of stem cell research, our paper does not posit a personal moral stance nor delve into the “when” of human life begins. To read further about the philosophical debate, consider the following sources:

Sandel M. J. (2004). Embryo ethics--the moral logic of stem-cell research.  The New England journal of medicine ,  351 (3), 207–209. https://doi.org/10.1056/NEJMp048145 ; George, R. P., & Lee, P. (2020, September 26). Acorns and Embryos . The New Atlantis. https://www.thenewatlantis.com/publications/acorns-and-embryos ; Sagan, A., & Singer, P. (2007). The moral status of stem cells. Metaphilosophy , 38 (2/3), 264–284. http://www.jstor.org/stable/24439776 ; McHugh P. R. (2004). Zygote and "clonote"--the ethical use of embryonic stem cells.  The New England journal of medicine ,  351 (3), 209–211. https://doi.org/10.1056/NEJMp048147 ; Kurjak, A., & Tripalo, A. (2004). The facts and doubts about beginning of the human life and personality.  Bosnian journal of basic medical sciences ,  4 (1), 5–14. https://doi.org/10.17305/bjbms.2004.3453

[6] Vazin, T., & Freed, W. J. (2010). Human embryonic stem cells: derivation, culture, and differentiation: a review.  Restorative neurology and neuroscience ,  28 (4), 589–603. https://doi.org/10.3233/RNN-2010-0543

[7] Socially, at its core, the Western approach to ethics is widely principle-based, autonomy being one of the key factors to ensure a fundamental respect for persons within research. For information regarding autonomy in research, see: Department of Health, Education, and Welfare, & National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research (1978). The Belmont Report. Ethical principles and guidelines for the protection of human subjects of research.; For a more in-depth review of autonomy within the US, see: Beauchamp, T. L., & Childress, J. F. (1994). Principles of Biomedical Ethics . Oxford University Press.

[8] Sherley v. Sebelius , 644 F.3d 388 (D.C. Cir. 2011), citing 45 C.F.R. 46.204(b) and [42 U.S.C. § 289g(b)]. https://www.cadc.uscourts.gov/internet/opinions.nsf/6c690438a9b43dd685257a64004ebf99/$file/11-5241-1391178.pdf

[9] Stem Cell Research Enhancement Act of 2005, H. R. 810, 109 th Cong. (2001). https://www.govtrack.us/congress/bills/109/hr810/text ; Bush, G. W. (2006, July 19). Message to the House of Representatives . National Archives and Records Administration. https://georgewbush-whitehouse.archives.gov/news/releases/2006/07/20060719-5.html

[10] National Archives and Records Administration. (2009, March 9). Executive order 13505 -- removing barriers to responsible scientific research involving human stem cells . National Archives and Records Administration. https://obamawhitehouse.archives.gov/the-press-office/removing-barriers-responsible-scientific-research-involving-human-stem-cells

[11] Hurlbut, W. B. (2006). Science, Religion, and the Politics of Stem Cells.  Social Research ,  73 (3), 819–834. http://www.jstor.org/stable/40971854

[12] Akpa-Inyang, Francis & Chima, Sylvester. (2021). South African traditional values and beliefs regarding informed consent and limitations of the principle of respect for autonomy in African communities: a cross-cultural qualitative study. BMC Medical Ethics . 22. 10.1186/s12910-021-00678-4.

[13] Source for further reading: Tangwa G. B. (2007). Moral status of embryonic stem cells: perspective of an African villager. Bioethics , 21(8), 449–457. https://doi.org/10.1111/j.1467-8519.2007.00582.x , see also Mnisi, F. M. (2020). An African analysis based on ethics of Ubuntu - are human embryonic stem cell patents morally justifiable? African Insight , 49 (4).

[14] Jecker, N. S., & Atuire, C. (2021). Bioethics in Africa: A contextually enlightened analysis of three cases. Developing World Bioethics , 22 (2), 112–122. https://doi.org/10.1111/dewb.12324

[15] Jecker, N. S., & Atuire, C. (2021). Bioethics in Africa: A contextually enlightened analysis of three cases. Developing World Bioethics, 22(2), 112–122. https://doi.org/10.1111/dewb.12324

[16] Jackson, C.S., Pepper, M.S. Opportunities and barriers to establishing a cell therapy programme in South Africa.  Stem Cell Res Ther   4 , 54 (2013). https://doi.org/10.1186/scrt204 ; Pew Research Center. (2014, May 1). Public health a major priority in African nations . Pew Research Center’s Global Attitudes Project. https://www.pewresearch.org/global/2014/05/01/public-health-a-major-priority-in-african-nations/

[17] Department of Health Republic of South Africa. (2021). Health Research Priorities (revised) for South Africa 2021-2024 . National Health Research Strategy. https://www.health.gov.za/wp-content/uploads/2022/05/National-Health-Research-Priorities-2021-2024.pdf

[18] Oosthuizen, H. (2013). Legal and Ethical Issues in Stem Cell Research in South Africa. In: Beran, R. (eds) Legal and Forensic Medicine. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-32338-6_80 , see also: Gaobotse G (2018) Stem Cell Research in Africa: Legislation and Challenges. J Regen Med 7:1. doi: 10.4172/2325-9620.1000142

[19] United States Bureau of Citizenship and Immigration Services. (1998). Tunisia: Information on the status of Christian conversions in Tunisia . UNHCR Web Archive. https://webarchive.archive.unhcr.org/20230522142618/https://www.refworld.org/docid/3df0be9a2.html

[20] Gaobotse, G. (2018) Stem Cell Research in Africa: Legislation and Challenges. J Regen Med 7:1. doi: 10.4172/2325-9620.1000142

[21] Kooli, C. Review of assisted reproduction techniques, laws, and regulations in Muslim countries.  Middle East Fertil Soc J   24 , 8 (2020). https://doi.org/10.1186/s43043-019-0011-0 ; Gaobotse, G. (2018) Stem Cell Research in Africa: Legislation and Challenges. J Regen Med 7:1. doi: 10.4172/2325-9620.1000142

[22] Pang M. C. (1999). Protective truthfulness: the Chinese way of safeguarding patients in informed treatment decisions. Journal of medical ethics , 25(3), 247–253. https://doi.org/10.1136/jme.25.3.247

[23] Wang, L., Wang, F., & Zhang, W. (2021). Bioethics in China’s biosecurity law: Forms, effects, and unsettled issues. Journal of law and the biosciences , 8(1).  https://doi.org/10.1093/jlb/lsab019 https://academic.oup.com/jlb/article/8/1/lsab019/6299199

[24] Wang, Y., Xue, Y., & Guo, H. D. (2022). Intervention effects of traditional Chinese medicine on stem cell therapy of myocardial infarction.  Frontiers in pharmacology ,  13 , 1013740. https://doi.org/10.3389/fphar.2022.1013740

[25] Li, X.-T., & Zhao, J. (2012). Chapter 4: An Approach to the Nature of Qi in TCM- Qi and Bioenergy. In Recent Advances in Theories and Practice of Chinese Medicine (p. 79). InTech.

[26] Luo, D., Xu, Z., Wang, Z., & Ran, W. (2021). China's Stem Cell Research and Knowledge Levels of Medical Practitioners and Students.  Stem cells international ,  2021 , 6667743. https://doi.org/10.1155/2021/6667743

[27] Luo, D., Xu, Z., Wang, Z., & Ran, W. (2021). China's Stem Cell Research and Knowledge Levels of Medical Practitioners and Students.  Stem cells international ,  2021 , 6667743. https://doi.org/10.1155/2021/6667743

[28] Zhang, J. Y. (2017). Lost in translation? accountability and governance of Clinical Stem Cell Research in China. Regenerative Medicine , 12 (6), 647–656. https://doi.org/10.2217/rme-2017-0035

[29] Wang, L., Wang, F., & Zhang, W. (2021). Bioethics in China’s biosecurity law: Forms, effects, and unsettled issues. Journal of law and the biosciences , 8(1).  https://doi.org/10.1093/jlb/lsab019 https://academic.oup.com/jlb/article/8/1/lsab019/6299199

[30] Chen, H., Wei, T., Wang, H.  et al.  Association of China’s two-child policy with changes in number of births and birth defects rate, 2008–2017.  BMC Public Health   22 , 434 (2022). https://doi.org/10.1186/s12889-022-12839-0

[31] Azuma, K. Regulatory Landscape of Regenerative Medicine in Japan.  Curr Stem Cell Rep   1 , 118–128 (2015). https://doi.org/10.1007/s40778-015-0012-6

[32] Harris, R. (2005, May 19). Researchers Report Advance in Stem Cell Production . NPR. https://www.npr.org/2005/05/19/4658967/researchers-report-advance-in-stem-cell-production

[33] Park, S. (2012). South Korea steps up stem-cell work.  Nature . https://doi.org/10.1038/nature.2012.10565

[34] Resnik, D. B., Shamoo, A. E., & Krimsky, S. (2006). Fraudulent human embryonic stem cell research in South Korea: lessons learned.  Accountability in research ,  13 (1), 101–109. https://doi.org/10.1080/08989620600634193 .

[35] Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: interviews with researchers from Saudi Arabia. BMC medical ethics, 21(1), 35. https://doi.org/10.1186/s12910-020-00482-6

[36] Association for the Advancement of Blood and Biotherapies.  https://www.aabb.org/regulatory-and-advocacy/regulatory-affairs/regulatory-for-cellular-therapies/international-competent-authorities/saudi-arabia

[37] Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: Interviews with researchers from Saudi Arabia.  BMC medical ethics ,  21 (1), 35. https://doi.org/10.1186/s12910-020-00482-6

[38] Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: Interviews with researchers from Saudi Arabia. BMC medical ethics , 21(1), 35. https://doi.org/10.1186/s12910-020-00482-6

Culturally, autonomy practices follow a relational autonomy approach based on a paternalistic deontological health care model. The adherence to strict international research policies and religious pillars within the regulatory environment is a great foundation for research ethics. However, there is a need to develop locally targeted ethics approaches for research (as called for in Alahmad, G., Aljohani, S., & Najjar, M. F. (2020). Ethical challenges regarding the use of stem cells: interviews with researchers from Saudi Arabia. BMC medical ethics, 21(1), 35. https://doi.org/10.1186/s12910-020-00482-6), this decision-making approach may help advise a research decision model. For more on the clinical cultural autonomy approaches, see: Alabdullah, Y. Y., Alzaid, E., Alsaad, S., Alamri, T., Alolayan, S. W., Bah, S., & Aljoudi, A. S. (2022). Autonomy and paternalism in Shared decision‐making in a Saudi Arabian tertiary hospital: A cross‐sectional study. Developing World Bioethics , 23 (3), 260–268. https://doi.org/10.1111/dewb.12355 ; Bukhari, A. A. (2017). Universal Principles of Bioethics and Patient Rights in Saudi Arabia (Doctoral dissertation, Duquesne University). https://dsc.duq.edu/etd/124; Ladha, S., Nakshawani, S. A., Alzaidy, A., & Tarab, B. (2023, October 26). Islam and Bioethics: What We All Need to Know . Columbia University School of Professional Studies. https://sps.columbia.edu/events/islam-and-bioethics-what-we-all-need-know

[39] Ababneh, M. A., Al-Azzam, S. I., Alzoubi, K., Rababa’h, A., & Al Demour, S. (2021). Understanding and attitudes of the Jordanian public about clinical research ethics.  Research Ethics ,  17 (2), 228-241.  https://doi.org/10.1177/1747016120966779

[40] Ababneh, M. A., Al-Azzam, S. I., Alzoubi, K., Rababa’h, A., & Al Demour, S. (2021). Understanding and attitudes of the Jordanian public about clinical research ethics.  Research Ethics ,  17 (2), 228-241.  https://doi.org/10.1177/1747016120966779

[41] Dajani, R. (2014). Jordan’s stem-cell law can guide the Middle East.  Nature  510, 189. https://doi.org/10.1038/510189a

[42] Dajani, R. (2014). Jordan’s stem-cell law can guide the Middle East.  Nature  510, 189. https://doi.org/10.1038/510189a

[43] The EU’s definition of autonomy relates to the capacity for creating ideas, moral insight, decisions, and actions without constraint, personal responsibility, and informed consent. However, the EU views autonomy as not completely able to protect individuals and depends on other principles, such as dignity, which “expresses the intrinsic worth and fundamental equality of all human beings.” Rendtorff, J.D., Kemp, P. (2019). Four Ethical Principles in European Bioethics and Biolaw: Autonomy, Dignity, Integrity and Vulnerability. In: Valdés, E., Lecaros, J. (eds) Biolaw and Policy in the Twenty-First Century. International Library of Ethics, Law, and the New Medicine, vol 78. Springer, Cham. https://doi.org/10.1007/978-3-030-05903-3_3

[44] Council of Europe. Convention for the protection of Human Rights and Dignity of the Human Being with regard to the Application of Biology and Medicine: Convention on Human Rights and Biomedicine (ETS No. 164) https://www.coe.int/en/web/conventions/full-list?module=treaty-detail&treatynum=164 (forbidding the creation of embryos for research purposes only, and suggests embryos in vitro have protections.); Also see Drabiak-Syed B. K. (2013). New President, New Human Embryonic Stem Cell Research Policy: Comparative International Perspectives and Embryonic Stem Cell Research Laws in France.  Biotechnology Law Report ,  32 (6), 349–356. https://doi.org/10.1089/blr.2013.9865

[45] Rendtorff, J.D., Kemp, P. (2019). Four Ethical Principles in European Bioethics and Biolaw: Autonomy, Dignity, Integrity and Vulnerability. In: Valdés, E., Lecaros, J. (eds) Biolaw and Policy in the Twenty-First Century. International Library of Ethics, Law, and the New Medicine, vol 78. Springer, Cham. https://doi.org/10.1007/978-3-030-05903-3_3

[46] Tomuschat, C., Currie, D. P., Kommers, D. P., & Kerr, R. (Trans.). (1949, May 23). Basic law for the Federal Republic of Germany. https://www.btg-bestellservice.de/pdf/80201000.pdf

[47] Regulation of Stem Cell Research in Germany . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-germany

[48] Regulation of Stem Cell Research in Finland . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-finland

[49] Regulation of Stem Cell Research in Spain . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-spain

[50] Some sources to consider regarding ethics models or regulatory oversights of other cultures not covered:

Kara MA. Applicability of the principle of respect for autonomy: the perspective of Turkey. J Med Ethics. 2007 Nov;33(11):627-30. doi: 10.1136/jme.2006.017400. PMID: 17971462; PMCID: PMC2598110.

Ugarte, O. N., & Acioly, M. A. (2014). The principle of autonomy in Brazil: one needs to discuss it ...  Revista do Colegio Brasileiro de Cirurgioes ,  41 (5), 374–377. https://doi.org/10.1590/0100-69912014005013

Bharadwaj, A., & Glasner, P. E. (2012). Local cells, global science: The rise of embryonic stem cell research in India . Routledge.

For further research on specific European countries regarding ethical and regulatory framework, we recommend this database: Regulation of Stem Cell Research in Europe . Eurostemcell. (2017, April 26). https://www.eurostemcell.org/regulation-stem-cell-research-europe   

[51] Klitzman, R. (2006). Complications of culture in obtaining informed consent. The American Journal of Bioethics, 6(1), 20–21. https://doi.org/10.1080/15265160500394671 see also: Ekmekci, P. E., & Arda, B. (2017). Interculturalism and Informed Consent: Respecting Cultural Differences without Breaching Human Rights.  Cultura (Iasi, Romania) ,  14 (2), 159–172.; For why trust is important in research, see also: Gray, B., Hilder, J., Macdonald, L., Tester, R., Dowell, A., & Stubbe, M. (2017). Are research ethics guidelines culturally competent?  Research Ethics ,  13 (1), 23-41.  https://doi.org/10.1177/1747016116650235

[52] The Qur'an  (M. Khattab, Trans.). (1965). Al-Mu’minun, 23: 12-14. https://quran.com/23

[53] Lenfest, Y. (2017, December 8). Islam and the beginning of human life . Bill of Health. https://blog.petrieflom.law.harvard.edu/2017/12/08/islam-and-the-beginning-of-human-life/

[54] Aksoy, S. (2005). Making regulations and drawing up legislation in Islamic countries under conditions of uncertainty, with special reference to embryonic stem cell research. Journal of Medical Ethics , 31: 399-403.; see also: Mahmoud, Azza. "Islamic Bioethics: National Regulations and Guidelines of Human Stem Cell Research in the Muslim World." Master's thesis, Chapman University, 2022. https://doi.org/10.36837/ chapman.000386

[55] Rashid, R. (2022). When does Ensoulment occur in the Human Foetus. Journal of the British Islamic Medical Association , 12 (4). ISSN 2634 8071. https://www.jbima.com/wp-content/uploads/2023/01/2-Ethics-3_-Ensoulment_Rafaqat.pdf.

[56] Sivaraman, M. & Noor, S. (2017). Ethics of embryonic stem cell research according to Buddhist, Hindu, Catholic, and Islamic religions: perspective from Malaysia. Asian Biomedicine,8(1) 43-52.  https://doi.org/10.5372/1905-7415.0801.260

[57] Jafari, M., Elahi, F., Ozyurt, S. & Wrigley, T. (2007). 4. Religious Perspectives on Embryonic Stem Cell Research. In K. Monroe, R. Miller & J. Tobis (Ed.),  Fundamentals of the Stem Cell Debate: The Scientific, Religious, Ethical, and Political Issues  (pp. 79-94). Berkeley: University of California Press.  https://escholarship.org/content/qt9rj0k7s3/qt9rj0k7s3_noSplash_f9aca2e02c3777c7fb76ea768ba458f0.pdf https://doi.org/10.1525/9780520940994-005

[58] Lecso, P. A. (1991). The Bodhisattva Ideal and Organ Transplantation.  Journal of Religion and Health ,  30 (1), 35–41. http://www.jstor.org/stable/27510629 ; Bodhisattva, S. (n.d.). The Key of Becoming a Bodhisattva . A Guide to the Bodhisattva Way of Life. http://www.buddhism.org/Sutras/2/BodhisattvaWay.htm

[59] There is no explicit religious reference to when life begins or how to conduct research that interacts with the concept of life. However, these are relevant verses pertaining to how the fetus is viewed. (( King James Bible . (1999). Oxford University Press. (original work published 1769))

Jerimiah 1: 5 “Before I formed thee in the belly I knew thee; and before thou camest forth out of the womb I sanctified thee…”

In prophet Jerimiah’s insight, God set him apart as a person known before childbirth, a theme carried within the Psalm of David.

Psalm 139: 13-14 “…Thou hast covered me in my mother's womb. I will praise thee; for I am fearfully and wonderfully made…”

These verses demonstrate David’s respect for God as an entity that would know of all man’s thoughts and doings even before birth.

[60] It should be noted that abortion is not supported as well.

[61] The Vatican. (1987, February 22). Instruction on Respect for Human Life in Its Origin and on the Dignity of Procreation Replies to Certain Questions of the Day . Congregation For the Doctrine of the Faith. https://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_19870222_respect-for-human-life_en.html

[62] The Vatican. (2000, August 25). Declaration On the Production and the Scientific and Therapeutic Use of Human Embryonic Stem Cells . Pontifical Academy for Life. https://www.vatican.va/roman_curia/pontifical_academies/acdlife/documents/rc_pa_acdlife_doc_20000824_cellule-staminali_en.html ; Ohara, N. (2003). Ethical Consideration of Experimentation Using Living Human Embryos: The Catholic Church’s Position on Human Embryonic Stem Cell Research and Human Cloning. Department of Obstetrics and Gynecology . Retrieved from https://article.imrpress.com/journal/CEOG/30/2-3/pii/2003018/77-81.pdf.

[63] Smith, G. A. (2022, May 23). Like Americans overall, Catholics vary in their abortion views, with regular mass attenders most opposed . Pew Research Center. https://www.pewresearch.org/short-reads/2022/05/23/like-americans-overall-catholics-vary-in-their-abortion-views-with-regular-mass-attenders-most-opposed/

[64] Rosner, F., & Reichman, E. (2002). Embryonic stem cell research in Jewish law. Journal of halacha and contemporary society , (43), 49–68.; Jafari, M., Elahi, F., Ozyurt, S. & Wrigley, T. (2007). 4. Religious Perspectives on Embryonic Stem Cell Research. In K. Monroe, R. Miller & J. Tobis (Ed.),  Fundamentals of the Stem Cell Debate: The Scientific, Religious, Ethical, and Political Issues  (pp. 79-94). Berkeley: University of California Press.  https://escholarship.org/content/qt9rj0k7s3/qt9rj0k7s3_noSplash_f9aca2e02c3777c7fb76ea768ba458f0.pdf https://doi.org/10.1525/9780520940994-005

[65] Schenker J. G. (2008). The beginning of human life: status of embryo. Perspectives in Halakha (Jewish Religious Law).  Journal of assisted reproduction and genetics ,  25 (6), 271–276. https://doi.org/10.1007/s10815-008-9221-6

[66] Ruttenberg, D. (2020, May 5). The Torah of Abortion Justice (annotated source sheet) . Sefaria. https://www.sefaria.org/sheets/234926.7?lang=bi&with=all&lang2=en

[67] Jafari, M., Elahi, F., Ozyurt, S. & Wrigley, T. (2007). 4. Religious Perspectives on Embryonic Stem Cell Research. In K. Monroe, R. Miller & J. Tobis (Ed.),  Fundamentals of the Stem Cell Debate: The Scientific, Religious, Ethical, and Political Issues  (pp. 79-94). Berkeley: University of California Press.  https://escholarship.org/content/qt9rj0k7s3/qt9rj0k7s3_noSplash_f9aca2e02c3777c7fb76ea768ba458f0.pdf https://doi.org/10.1525/9780520940994-005

[68] Gert, B. (2007). Common morality: Deciding what to do . Oxford Univ. Press.

[69] World Medical Association (2013). World Medical Association Declaration of Helsinki: ethical principles for medical research involving human subjects. JAMA , 310(20), 2191–2194. https://doi.org/10.1001/jama.2013.281053 Declaration of Helsinki – WMA – The World Medical Association .; see also: National Commission for the Protection of Human Subjects of Biomedical and Behavioral Research. (1979).  The Belmont report: Ethical principles and guidelines for the protection of human subjects of research . U.S. Department of Health and Human Services.  https://www.hhs.gov/ohrp/regulations-and-policy/belmont-report/read-the-belmont-report/index.html

[70] Zakarin Safier, L., Gumer, A., Kline, M., Egli, D., & Sauer, M. V. (2018). Compensating human subjects providing oocytes for stem cell research: 9-year experience and outcomes.  Journal of assisted reproduction and genetics ,  35 (7), 1219–1225. https://doi.org/10.1007/s10815-018-1171-z https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6063839/ see also: Riordan, N. H., & Paz Rodríguez, J. (2021). Addressing concerns regarding associated costs, transparency, and integrity of research in recent stem cell trial. Stem Cells Translational Medicine , 10 (12), 1715–1716. https://doi.org/10.1002/sctm.21-0234

[71] Klitzman, R., & Sauer, M. V. (2009). Payment of egg donors in stem cell research in the USA.  Reproductive biomedicine online ,  18 (5), 603–608. https://doi.org/10.1016/s1472-6483(10)60002-8

[72] Krosin, M. T., Klitzman, R., Levin, B., Cheng, J., & Ranney, M. L. (2006). Problems in comprehension of informed consent in rural and peri-urban Mali, West Africa.  Clinical trials (London, England) ,  3 (3), 306–313. https://doi.org/10.1191/1740774506cn150oa

[73] Veatch, Robert M.  Hippocratic, Religious, and Secular Medical Ethics: The Points of Conflict . Georgetown University Press, 2012.

[74] Msoroka, M. S., & Amundsen, D. (2018). One size fits not quite all: Universal research ethics with diversity.  Research Ethics ,  14 (3), 1-17.  https://doi.org/10.1177/1747016117739939

[75] Pirzada, N. (2022). The Expansion of Turkey’s Medical Tourism Industry.  Voices in Bioethics ,  8 . https://doi.org/10.52214/vib.v8i.9894

[76] Stem Cell Tourism: False Hope for Real Money . Harvard Stem Cell Institute (HSCI). (2023). https://hsci.harvard.edu/stem-cell-tourism , See also: Bissassar, M. (2017). Transnational Stem Cell Tourism: An ethical analysis.  Voices in Bioethics ,  3 . https://doi.org/10.7916/vib.v3i.6027

[77] Song, P. (2011) The proliferation of stem cell therapies in post-Mao China: problematizing ethical regulation,  New Genetics and Society , 30:2, 141-153, DOI:  10.1080/14636778.2011.574375

[78] Dajani, R. (2014). Jordan’s stem-cell law can guide the Middle East.  Nature  510, 189. https://doi.org/10.1038/510189a

[79] International Society for Stem Cell Research. (2024). Standards in stem cell research . International Society for Stem Cell Research. https://www.isscr.org/guidelines/5-standards-in-stem-cell-research

[80] Benjamin, R. (2013). People’s science bodies and rights on the Stem Cell Frontier . Stanford University Press.

Olivia Bowers

MS Bioethics Columbia University (Disclosure: affiliated with Voices in Bioethics)

Mifrah Hayath

SM Candidate Harvard Medical School, MS Biotechnology Johns Hopkins University

Article Details

This work is licensed under a Creative Commons Attribution 4.0 International License .

Analysis of damage evolution and study on mesoscopic damage constitutive model of granite under freeze–thaw cycling

• Original Paper
• Published: 16 May 2024
• Volume 83 , article number  236 , ( 2024 )

Cite this article

• Sibo Jia 1 ,
• Qingyang Yu 1 ,
• Huichao Yin 2 ,
• Zhenxue Dai 1 ,
• Shangxian Yin 3 ,
• Yimeng Kong 1 ,
• Hung Vo Thanh 4 , 5 , 6 &
• Mohamad Reza Soltanian 7  

The failure of rocks in seasonal frozen areas under freeze–thaw cycles (FTCs) is a frequently problem in engineering construction, posing a huge threat to the stability of the engineering. In order to explore the mechanism of rock damage degradation. It is necessary to analyze the damage evolution process of rocks and establish an accurate FTCs rock damage constitutive model. Taking the granite in the seasonal frozen zone of Northeast China as the research object, the macro and meso parameters and microstructure of the FTCs granite were analyzed through indoor tests. A new method is proposed to define damage variables considering mesoscopic parameters to establish a mesoscopic damage constitutive model for rocks, further revealing the damage mechanism and failure law of rocks under freeze–thaw load coupling. The research results indicate that in the early stage of FTCs, 20 cycles contribute significantly to the damage and deterioration of rocks, accounting for about 50% of the 80 cycles. After 20 cycles, the degradation trend of various macroscopic and mesoscopic parameters is relatively slow. The residual strain of the rock accumulates as the number of FTCs increases, the brittleness of the rock weakens, and the plasticity strengthens. Based on the established new method of considering mesoscopic parameter damage variables, the viewpoint of introducing correction coefficients based on statistical constitutive models has been validated. After uniaxial compression test data verification, the model has shown good performance. This model expands the damage model of rock freeze–thaw compression coupling effect, providing reference for research on FTCs related to rocks.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Price includes VAT (Russian Federation)

Instant access to the full article PDF.

Rent this article via DeepDyve

Institutional subscriptions

Data Availability

This article introduces the available data generated during this study.

Amiri SAG, Grimstad G, Kadivar M et al (2016) Constitutive model for rate-independent behavior of saturated frozen soi-ls. Can Geotech J 53(10):1646–1657. https://doi.org/10.1139/cgj-2015-0467

Article   Google Scholar  

Ahmadi S, Ghasemzadeh H, Changizi F (2021a) Effects of a low-carbon emission additive on mechanical properties of finegrained soil under freeze-thaw cycles. J Clean Prod 304:127157. https://doi.org/10.1016/j.jclepro.2021.127157

Article   CAS   Google Scholar  

Ahmadi S, Ghasemzadeh H, Changizi F (2021b) Effects of thermal cycles on microstructural and functional properties of nano treated clayey soil. Eng Geol 280:105929. https://doi.org/10.1016/j.enggeo.2020.105929

Chen RS, Kang ES, Wu LZ et al (2005) Discussion on the Distribution of Cold Regions in China [J]. Glacier Frozen so-Il 27(4):469–475 ( (in Chinese) )

Google Scholar  

Chu Y, Zhang D, Song S, et al (2023) Experimental study on the evolution of pore structure of coal samples under freeze–thaw. Physics of Fluids 35(3). https://doi.org/10.1063/5.0145187

Freire-Lista D M, Fort R, Varas-Muriel M J (2015) Freeze–thaw fracturing in building granites. Cold Regions Science and Technology 113: 40–51. https://doi.org/10.1016/j.coldregions.2015.01.008

Ghobadi MH, Babazadeh R (2014) Experimental studies on the effects of cyclic freezing–thawing, salt crystallization, and thermal shock on the physical and mechanical characteristics of selected sandstones. Rock Mech Rock Eng 48(3):1001–1016. https://doi.org/10.1007/s00603-014-0609-6

Ghasemzadeh H, Ghoreishian Amiri SA (2013) A hydro-mechanical elastoplastic model for unsaturated soils under isotropic loading conditions. Comput Geotech 51:91–100. https://doi.org/10.1016/j.compgeo.2013.02.006

Ghasemzadeh H, Sojoudi MH, Ghoreishian Amiri SA et al (2017) Elastoplastic model for hydro-mechanical behavior of unsaturated soils. Soils Found 57(3):371–383. https://doi.org/10.1016/j.sandf.2017.05.005

Ghoreishian Amiri SA, Grimstad G, Kadivar M (2022) An elastic-viscoplastic model for saturated frozen soils. Eur J Environ Civ En 26(7):2537–2553. https://doi.org/10.1080/19648189.2016.1271361

Huang SB, Liu QS, Cheng AP, Liu YZ et al (2018) A statistical damage constitutive model under freeze-thaw and loading for rock and its engineering application. Cold Reg Sci Technol 145:142–150. https://doi.org/10.1016/j.coldregions.2017.10.015

Huang SB, Ye Y, Cui X et al (2020) Theoretical and experimental study of the frost heaving characteristics of the saturated sandstone under low temperature. Cold Reg Sci Technol 174:103036. https://doi.org/10.1016/j.coldregions.2020.103036

Inada Y, Yokota K (1984) Some studies of low temperature rock stength. Intl J RockMech Mining Sci Geomech Abstracts 21(3):145–153. https://doi.org/10.1016/0148-9062(84)91532-8

Jia H, Xiang W, Krautblatter M (2015) Quantifying Rock Fatigue and Decreasing Compressive and Tensile Strength after Repeated Freeze-Thaw Cycles. Permafrost Periglac Process 26:368–377. https://doi.org/10.1002/ppp.1857

Jia H, Ding S, Zi F et al (2020) Evolution in sandstone pore structures with freeze-thaw cycling and interpretation of damage mechanisms in saturated porous rocks. CATENA 195:104915. https://doi.org/10.1016/j.catena.2020.104915

Lemaitre J (1984) How to ues damage mechanics. Nucl Eng Des 80(3):233–245. https://doi.org/10.1016/0029-5493(84)90169-9

Liu QS, Xu XC (2000) Damage analysis of brittle rock under temperature[J]. J Rock Mech Eng 19(4):408–411 ( (in Chinese) )

Liu QS, Huang SB, Kang YS et al (2015) Research on rock mass freeze-thaw fatigue damage model and evaluation index[J]. J Rock Mech Eng 34(6):1116–1127 ( (in Chinese) )

CAS   Google Scholar  

Li SC, Xu J, Li KG (2007) Statistical constitutive model of rock damage based on the correction of initial damage coefficient[J]. J Sichuan Univ (Engineering Science Edition) 33(6):41–44 ( (in Chinese) )

Li B, Ren C, Wang Z et al (2020) Experimental study on damage and the permeability evolution process of methane-containing coal under different temperature conditions. J Petrol Sci Eng 184:106509. https://doi.org/10.1016/j.petrol.2019.106509

Li C, Jin J, Wu P et al (2022) Effect of Freeze-Thaw Cycles on Shear Strength of Tailings and Prediction by Grey Model. Minerals 12(9):1125. https://doi.org/10.3390/min12091125

Matsuoka H, Nakai T (1974) Stress-deformation and strength characteristics of soil three different principal stress. Pro-Ceedings of JSCE 2:59–70. https://doi.org/10.2208/JSCEJ1969.1974.232-59

Matsuoka H, Hoshikawa T, Ueno K (1990) A general failure criterion and stress-strain retain for granual materials to metals. Soil Found 30(2):119–127. https://doi.org/10.3208/sandf1972.30.2_119

Meng XZ, Zhang HM, Liu XY (2021) Rock damage constitutive model based on the modified logistic equation under freeze–thaw and load conditions. J Cold Regions Eng 35(4):04021016. https://doi.org/10.1061/(ASCE)CR.1943-5495.000026

Polak J (1991) Cyclic Plasticity and Low Cycle Fatigue Life of Metal. Elsevier, New York

Sondergeld CH, Rat CS (2005) Observations of velocity and resistivity changes during freeze-thaw cycles in Berea sand-stone. SEG Tech Program Expanded Abstracts 24(6):1509–1512. https://doi.org/10.1190/1.2147977

Satake M (1976) Stress-deformation and strength characteristics of soil three different principal stress(Discus-sion). Proc.of Japan Society of Civil Engineers 246:137–138.

Song CY (2018) Research and application of micro structural characteristics and deformation failure mechanism of weakly cemented sandstone[J]. J Rock Mech Eng 37(3):779 ( (in Chinese) )

Song YJ, Yang HM, Tan H et al (2021) Research on damage evolution characteristics of sandstone with different saturation under freezing and thawing environment[J]. J Rock Mech Eng 40(8):1513–1524 ( (in Chinese) )

Xu GM, Liu QS (2005) Analysis of rock freeze-thaw failure mechanism and experimental study on freeze-thaw mechanics[J]. J Rock Mech Eng 24(17):3076–3082 ( (in Chinese) )

Yang GS, Xi JM, Li HJ et al (2010) Experimental study on the characteristics of frozen Rock mechanics under three-dimensional stress[J]. J Rock Mech Eng 29(3):459–464 ( (in Chinese) )

Yu Q, Dai Z, Zhang Z et al (2018) Estimation of Sandstone Permeability with SEM Images Based on Fractal Theory. Transp Porous Media 126(3):0701–0712. https://doi.org/10.1007/s11242-018-1167-2

Yu Q, Xiong Z, Du C et al (2020) Identification of rock pore structures and permeabilities using electron microscopy experiments and deep learning interpretations. Fuel 268:117416. https://doi.org/10.1016/j.fuel.2020.117416

Yu Q, Lei P, Dai Z et al (2023) Damage Characteristics of Limestone under Freeze-Thaw Cycle for Tunnels in Seasonal Frozen Areas. Iranian J Sci Technol Trans Civil Eng 47(1):469–477. https://doi.org/10.1007/s40996-022-00979-7

Zhang QS, Yang GS, Ren JX (2003) A new approach to rock damage variables and constitutive equation[J]. J Rock Mech Eng 21(3):30–34 ( (in Chinese) )

Zhang HM, Lei LN, Yang GS (2014) Rock damage model based on Weibull statistical distribution[J]. J Hunan Univ Sci Technol (natural Science Edition) 29(3):29–32 ( (in Chinese) )

Zhang HM, Zhang MJ, Xie XM et al (2015) Experimental study on physical and mechanical properties of red sandstone under freeze-thaw cycle[J]. J Taiyuan Univ Technol 46(1):69–74 ( (in Chinese) )

Zhang HM, Wang YF (2022) Multi scale analysis of damage evolution of freeze-thaw red sandstone. Geotech Mech 43(8):2103–2114. https://doi.org/10.16285/j.rsm.2021.1726

Zhao T, Yang GS, Xi JM et al (2019) Experimental study on macro and meso freeze-thaw damage characteristics of Cretaceous sandstone[J]. J Xi’an Univ Sci Technol 39(2):241–248 ( (in Chinese) )

Zhou ST, Jiang N, Luo XD et al (2020) Uniaxial compression fractal damage constitutive model of rock subjected to freezing and thawing. Periodica Polytech Civil Eng 64(2):500–510. https://doi.org/10.3311/PPci.15313

Zhang Q, Li XC, Gao JX et al (2022) Macro-and Meso-Damage Evolution Characteristics of Coal Using Acoustic Emission and Keuence Testing Technique. Nat Resour Res 31:517–534. https://doi.org/10.1007/s11053-021-10006-7

Zhang Q, Li XC, Li B et al (2023) Continuous-Discontinuous Element Numerical Modeling of Damage and Fracture Characteristics of a Loaded Coal. Nat Resour Res 32:373–389. https://doi.org/10.1007/s11053-022-10147-3

Download references

Acknowledgements

This work is funded by the National Natural Science Foundation of China (NSFC: U2267217, 42141011, 42002254).

Author information

Authors and affiliations.

College of Construction Engineering, Jilin University, Changchun, 130026, China

Sibo Jia, Qingyang Yu, Zhenxue Dai & Yimeng Kong

Beijing and the School of Information Engineering, Institute of Disaster Prevention, China University of Mining and Technology, Langfang, 065201, China

Huichao Yin

North China Institute of Science & Technology, Langfang, 065201, China

Shangxian Yin

Laboratory for Computational Mechanics, Institute for Computational Science and Artificial Intelligence, Van Lang University, Ho Chi Minh City, Vietnam

Hung Vo Thanh

Faculty of Mechanical - Electrical and Computer Engineering, School of Technology, Van Lang University, Ho Chi Minh City, Vietnam

MEU Research Unit, Middle East University, Amman, Jordan

Departments of Geosciences and Environmental Engineering, University of Cincinnati, Cincinnati, OH, USA

Mohamad Reza Soltanian

You can also search for this author in PubMed   Google Scholar

Corresponding author

Correspondence to Qingyang Yu .

Ethics declarations

Competing interest.

The authors declare no competing financial interest.

Rights and permissions

Reprints and permissions

About this article

Jia, S., Yu, Q., Yin, H. et al. Analysis of damage evolution and study on mesoscopic damage constitutive model of granite under freeze–thaw cycling. Bull Eng Geol Environ 83 , 236 (2024). https://doi.org/10.1007/s10064-024-03741-7

Download citation

Received : 19 July 2023

Accepted : 09 May 2024

Published : 16 May 2024

DOI : https://doi.org/10.1007/s10064-024-03741-7

Share this article

Anyone you share the following link with will be able to read this content:

Sorry, a shareable link is not currently available for this article.

Provided by the Springer Nature SharedIt content-sharing initiative

• Freeze–thaw cycle
• Microscopic
• Freeze–thaw damage variables
• SMP criteria
• Constitutive model
• Find a journal
• Publish with us
• Track your research

• Reference Manager
• Simple TEXT file

People also looked at

Original research article, association between milk consumption and kidney stones in u.s. adults: results from nhanes 2007–2018.

• 1 Meizhou Clinical Institute of Shantou University Medical College, Meizhou, China
• 2 Department of Urology, Meizhou People's Hospital (Meizhou Academy of Medical Sciences), Meizhou, China
• 3 Department of Cardiology, Second Affiliated Hospital of Shantou University Medical College, Shantou, China

Background: Dietary strategies play a crucial role in the prevention of kidney stones. While milk is known for its rich nutritional content, its impact on kidney stone formation remains unclear. This study aimed to examine the relationship between milk consumption and the risk of kidney stones among U.S. adults.

Methods: We included 24,620 participants aged 20 and older from the National Health and Nutrition Examination Survey (2007–2018). Milk consumption was defined based on each participant’s response to the questionnaire item on “Past 30 day milk product consumption.” Kidney stones history was self-reported by participants. The analysis employed weighted multivariate logistic regression models, followed by subgroup analyses for result validation, and explored the age-related dynamics of milk consumption’s effect on kidney stone risk using a restricted cubic spline model.

Results: Adjusted findings revealed that higher milk intake was associated with a decreased risk of kidney stones (odds ratio [OR] = 0.90, 95% confidence interval [CI] 0.85–0.96), notably among women (OR = 0.86, 95% CI 0.80–0.92) but not significantly in men (OR = 0.94, 95% CI 0.86–1.02). Smoothed curves across all ages showed that women consuming milk had a lower incidence of kidney stones than those who did not, particularly with regular consumption.

Conclusion: This study uncovered that across all age groups, higher frequency of milk consumption in women is associated with a reduced risk of kidney stones. However, further prospective cohort studies are needed to confirm this finding.

1 Introduction

Kidney stones is a prevalent condition within the urinary tract system, characteristically presenting with symptoms such as unilateral abdominal discomfort, infections of the urinary tract, and hematuria. In its severest form, it can precipitate renal failure, significantly impairing patient quality of life ( 1 , 2 ). Epidemiological data from recent decades indicate a notable surge in both the incidence and prevalence of kidney stones, with global incidence rates estimated between 1 and 15%. Specifically, the incidence in the United States is reported at 11.0% ( 3 , 4 ). The therapeutic landscape for kidney stones predominantly involves costly surgical interventions. In the United States, the fiscal implications of kidney stones are profound, with annual healthcare costs attributed to this condition reaching into the billions and projected to escalate further, thereby imposing a considerable economic burden on both societal and individual levels ( 5 ). This scenario accentuates the necessity for more rigorous development and implementation of preventative strategies against kidney stones.

The pathogenesis of kidney stones is multifactorial, with genetic, dietary, behavioral, and inflammatory factors all playing contributory roles over time. Hence, targeting these underlying etiological factors or risk elements is recognized as the most effective method for prevention ( 6 ). Dietary interventions are highlighted as a critical preventative measure against the onset of kidney stones in daily life ( 7 ). Milk, an essential component of the human diet, is a rich source of proteins, lipids, a variety of vitamins, calcium, magnesium, and other trace elements ( 6 ). Research to date has demonstrated milk’s potential in mitigating the risk of various chronic conditions, including cardiovascular and cerebrovascular diseases, dementia, diabetes, and cancer ( 8 – 12 ). However, the impact of milk consumption on the risk of developing kidney stones remains unexplored. Disturbances in calcium and vitamin D metabolism within the human body are closely associated with the incidence of kidney stones ( 13 ). In the past, high dietary calcium intake was frequently perceived as a risk factor for the development of kidney stones. Contrarily, an increasing body of research collectively suggests that a high daily intake of dietary calcium is beneficial for the prevention of kidney stones ( 14 – 18 ). Additionally, preliminary studies suggest that increasing the intake of fluids, dietary magnesium may reduce the risk of kidney stones ( 6 , 19 ). Moreover, the Dietary Approaches to Stop Hypertension diet is associated with a decreased risk of kidney stones, with low-fat dairy products being a part of this dietary approach ( 20 ). Given milk’s established profile as a healthful beverage, this generates a scientific hypothesis that augmented milk consumption may confer protective effects against the formation of kidney stones.

Considering these considerations, an investigation into the relationship between milk intake and the risk of kidney stones could provide critical insights for the formulation of preventive measures, thereby fostering the advancement of global public health initiatives. This research employs a cross-sectional design, leveraging data from the National Health and Nutrition Examination Survey (NHANES) covering the years 2007 to 2018, to examine this potential correlation.

2 Materials and methods

2.1 study participants.

NHANES, conducted by the National Center for Health Statistics in the United States, is a continuous, stratified, multistage sampling survey that integrates structured interviews and physical examinations to comprehensively assess the health and nutritional status of the American adult and child populations. The sampling strategy and detailed information used in this study were obtained from the NHANES website. 1 Written consent was obtained from all participants involved in NHANES.

In this cross-sectional study, we utilized data from six consecutive cycles of NHANES spanning from 2007 to 2018. During these 12 years, a total of 59,842 participants were included. Initially, 25,072 participants under the age of 20 were excluded. Subsequently, we excluded 91 participants with incomplete kidney stones history information and 3,103 participants with incomplete data on milk consumption (consumption frequency and milk fat content), as well as 6,956 participants lacking information on covariates. Ultimately, this study identified 24,620 participants who met the inclusion criteria ( Figure 1 ).

Figure 1 . Flow chart for inclusion and exclusion of study participants. NHANES, National Health and Nutrition Examination Survey.

2.2 Exposure and outcome definitions

As the exposure variable, milk consumption was defined based on participants’ responses to the questionnaire item “Past 30 day milk product consumption.” Based on their responses, participants were categorized into four groups: (1) never, (2) rarely: less than once a week, (3) sometimes: once a week or more, but less than once a day, and (4) often: once a day or more. Additionally, we classified the type of milk consumed by participants into three categories based on the fat content of the milk: “1% fat milk” or “2% fat milk” was defined as semi-skimmed milk, while the other two categories were whole milk and skim milk.

Kidney stones history was designed as the outcome variable, determined by participants’ responses to the survey question “Ever had kidney stones?” The reliability of self-reported kidney stones history has been validated by relevant studies ( 21 ).

2.3 Covariates definition

To account for potential confounding factors, this study incorporated the following covariates based on insights from other research ( 22 ): age, body mass index (BMI), gender, race (non-Hispanic Black, non-Hispanic White, Mexican American, and other), marital status (married/living with partner and living alone), educational level (less than high school, high school or equivalent, and college degree or higher), household income and Poverty Income Ratio (PIR), history of smoking, history of alcohol consumption, recreational activities (inactive or moderate and vigorous), hypertension, and diabetes history. The PIR was divided into three groups: low (≤ 1.30), middle (>1.30, ≤ 3.50), and high (> 3.5). History of smoking, alcohol consumption, and hypertension were all recorded as “Yes/No,” while diabetes history was recorded as “Yes/No/Borderline.”

2.4 Statistical analysis

To enhance the national representativeness of our sample, we employed weighted analysis to mitigate the effects of the complex multi-stage sampling design, adhering to the sample weighting data, and merging methods recommended by NHANES. In the baseline characteristics table, continuous variables were presented using a weighted mean with standard error (SE), whereas categorical variables were reported as the number of observations with weighted percentages (%). Weighted linear regression for continuous variables and weighted Chi-square tests for categorical variables were utilized to assess differences between populations with and without kidney stones formation.

Considering the sample weights in the survey, we employed weighted multivariate logistic regression models to explore the relationship between milk consumption and the prevalence of kidney stones. We utilized three models in our analysis: Model 1 did not adjust for any covariates, Model 2 was adjusted for age, gender, and race only, and Model 3 was further adjusted for a comprehensive set of variables including age, gender, race, educational level, marital status, PIR, BMI, smoking history, alcohol consumption history, physical activity (leisure activities), hypertension, and diabetes. Based on the results of the weighted logistic regression analysis, we also conducted trend tests to better assess the overall impact brought by changes in milk consumption.

To assess the robustness of the relationship between milk consumption and the prevalence of kidney stones across different populations, subgroup analyses were conducted within the context of regression Model 3, utilizing interaction terms to identify specific population segments where the relationship might differ. Each subgroup included an interaction term, and the interaction among subgroups was evaluated using the log-likelihood ratio test. In these subgroup analyses, continuous variables were treated as categorical, with age being divided into two groups at the threshold of 60 years and BMI at the threshold of 25 kg/m^2. Regression Model III was then reapplied to study the specific impact of milk consumption on the prevalence of kidney stones in these populations. Restricted cubic splines (RCS) model is a powerful tool for describing the dose–response relationships between continuous exposure and outcomes ( 23 ). We aim to use this model to explore the effects of certain continuous variables on the incidence of kidney stones across different levels of milk consumption. Recently, a study by Park et al., which conducted a dose–response analysis on the impact of varying levels of coffee consumption across all ages on mortality, clearly demonstrated the effect on mortality rates ( 24 ). Given that age has been identified as a significant factor in the incidence of kidney stones ( 21 ), RCS model was utilized to plot smooth curves to better explore the impact of milk consumption on the prevalence of kidney stones across different ages. Following this, based on the curves, piecewise linear regression models were applied to identify the threshold effect of age on the prevalence of kidney stones and to detect the inflection point where the relationship begins to change significantly ( 25 ).

All statistical analyses in this study were conducted using R software 2 (version 4.3.2) and EmpowerStats 3 (X&Y Solutions, Inc., Boston, MA) for both statistical analysis and graphing purposes. Statistical significance was determined by a two-sided p-value of 0.05.

3.1 Characteristics of the study population

The study included a total of 24,620 participants, among which 2,396 individuals reported having been diagnosed with kidney stones ( Table 1 ). Statistically significant differences were observed across most baseline characteristics when participants were divided into groups based on their history of kidney stones. Compared to the non-kidney stones group, kidney stones patients were older on average (53.27 years), had a higher average BMI (30.83 kg/m^2), a higher proportion of males (55.92%), a higher proportion of non-Hispanic whites (78.55%), a higher proportion of those who were not single (69.75%), a higher proportion of smokers (50.76%), a higher proportion of individuals engaging in less vigorous activity (81.16%), and higher proportions of individuals with hypertension (47.37%) and diabetes (18.33%). In this study, the focus was particularly on the association between milk consumption and the prevalence of kidney stones. The data showed that individuals in the kidney stones group consumed milk less frequently across all categories (Rarely = 15.54%, Sometimes = 28.06%, Often = 33.58%), and a higher proportion of individuals never consumed milk (Never = 22.82%) compared to the non-kidney stones group (Never = 18.85%).

Table 1 . Baseline characteristics of participants between 2007 and 2018 (n = 24,620).

3.2 Associations between milk consumption and kidney stones

Weighted multivariable logistic regression analyses demonstrate a notable inverse relationship between the frequency of milk consumption and the risk of kidney stones ( Table 2 ). This association remains significant across several models: an unadjusted Model 1 [odds ratio (OR) = 0.94, 95% confidence interval (CI) 0.89–0.99], a minimally adjusted Model 2 (OR = 0.91, 95% CI 0.86–0.96), and a fully adjusted Model 3 (OR = 0.90, 95% CI 0.85–0.96). Compared to individuals who never consume milk, those who frequently consume milk (‘Often’) exhibit a significantly lower risk of developing kidney stones (OR = 0.71, 95% CI 0.60–0.83).

Moreover, the variety of milk types, specifically whole milk, semi-skimmed milk, and skim milk, which are commonly consumed in daily life, prompted a stratified analysis based on the fat content of milk. Overall, in Model 3, regardless of the type of milk, the frequency of milk consumption was inversely associated with the prevalence of kidney stones. Intriguingly, the protective effect of milk against kidney stones appears to strengthen with increasing degrees of fat removal. The results showed that whole milk (OR = 0.93, 95% CI 0.88–0.99), semi-skimmed milk (OR = 0.91, 95% CI 0.86–0.97), and skimmed milk (OR = 0.80. 95% CI 0.72–0.89).

3.3 Subgroup analysis

Subsequent subgroup analyses were conducted to evaluate the robustness of the link between milk intake and the incidence of kidney stones across diverse demographic cohorts ( Figure 2 ). Beyond the stratification variables themselves, adjustments were made for a comprehensive set of covariates including age, sex, race, educational attainment, marital status, PIR, BMI, smoking status, alcohol use, physical activity, hypertension, and diabetes mellitus. These analyses revealed that the inverse relationship between milk consumption and kidney stone prevalence remained unaltered across most subgroups, with no significant interaction effects observed ( P for interaction >0.05). However, gender emerged as a significant modifier of the relationship between milk intake and kidney stone risk, denoting a specific interaction ( P for interaction = 0.033). Next, our investigation will specifically explore the differential impact of milk consumption on kidney stone formation across genders.

Figure 2 . Subgroup analyses for the relationship between milk consumption and kidney stones. BMI, body mass index. Each stratification adjusted for all the factors (age, gender, race, education level, marital status, PIR, BMI, smoking, drinking, activity, hypertension, diabetes) except the stratification factor itself in model.

Table 2 . Weighted multivariable logistic regression for the association between milk consumption and kidney stones.

3.4 Association between milk consumption and kidney stones based on gender

In the regression model ( Table 3 ), there appears to be no significant association between the frequency of milk consumption and the prevalence of kidney stones among the male population (P for trend = 0.1647), with a notable negative correlation observed only within the ‘Rarely’ category of milk consumption (OR = 0.71, 95%CI 0.51–0.99). Conversely, for the female cohort, milk consumption significantly reduces the risk of kidney stone formation (OR = 0.86, 95%CI 0.80–0.92). Importantly, this trend becomes particularly evident with increasing frequency levels: ‘Rarely’ (OR = 0.77, 95%CI 0.60–0.99), ‘Sometimes’ (OR = 0.71, 95%CI 0.57–0.89), ‘Often’ (OR = 0.62, 95%CI 0.49–0.77).

Table 3 . Weighted multivariable logistic regression for the association between milk consumption and kidney stones based on gender.

3.5 With the age changing, association between milk consumption and kidney stones based on gender

As it is widely recognized, age is closely associated with the occurrence of kidney stones ( 21 ). Thus, to investigate the age-related variations in the impact of milk consumption on the prevalence of kidney stones, we employed RCS model to generate smooth fitting curves. The results ( Figures 3A – D ) demonstrated distinct gender-specific patterns in the influence of age on kidney stone prevalence. In males, the prevalence of kidney stones gradually increased with advancing age ( Figure 3A ). This trend remained consistent across different frequencies of milk consumption groups; however, milk consumption did not consistently reduce the prevalence of kidney stones in males across all age groups. Notably, we observed that milk consumption appeared to have a promotive effect on kidney stone occurrence in males until approximately the age of 40, after which this phenomenon reversed ( Figure 3B ).

Figure 3 . The relationship between age and the risk of kidney stones based on gender. (A,B) Smooth fitting curves in male. (C-E) Smooth fitting curves in female. OR, odds ratio; Rarely, less than once a week; Sometimes, once a week or more, but less than once a day; Often, once a day or more. Race, educational level, marital status, BMI, PIR, smoking, drinking, activity, hypertension, and diabetes were adjusted in model.

Moreover, we identified a nonlinear relationship between age and kidney stone prevalence in females, characterized by a clear inflection point in the curve ( Figure 3C ). Subsequently, through threshold effect analysis, we determined the numerical value of this inflection point. The risk of kidney stones in females increased with age up to 53 years (OR = 1.02, 95% CI 1.01–1.03), after which the risk decreased (OR = 0.98, 95% CI 0.97–0.99) ( Table 4 ). Furthermore, inflection points were observed in curves for other milk consumption frequencies (“Never,” “Rarely,” “Sometimes”), occurring at similar time frames. Surprisingly, the curve for “Often” consumption frequency displayed a distinctly different pattern, consistently maintaining a lower prevalence level of kidney stones. Across all age groups of females, any milk consumption frequency, compared to the “never” curve, reduced the risk of kidney stone prevalence ( Figure 3D ). Additionally, we found that with the inflection point at 53 years as a boundary, more frequent milk consumption led to a significant decrease in kidney stone prevalence among females in both age segments ( Figure 3E ).

Table 4 . Threshold effect analysis of age on kidney stones based on female using piecewise linear regression.

4 Discussion

To date, there have been no epidemiological studies reporting any association between milk consumption and kidney stone levels. In this cross-sectional study, which is nationally representative and based on the NHANES database, we observed that individuals who consumed milk more frequently had a reduced risk of developing kidney stones, with a more pronounced effect observed with higher degrees of milk skimming. Subgroup analyses revealed consistent results across all subgroups except for sex, where the protective effect of milk was evident only in women. The smooth fitting curve illustrated a nonlinear relationship between age and the prevalence of kidney stones among individuals with varying milk consumption levels. Notably, in women, the prevalence of kidney stones peaked at age 53 and then declined rapidly thereafter. Regardless of age, women who consumed milk exhibited lower rates of kidney stones compared to those who did not, particularly among regular milk consumers. These findings suggest that increasing milk intake may decrease the incidence of kidney stones, emphasizing the importance of milk consumption, especially among women.

Our study shows that milk is strongly associated with a reduced risk of kidney stones. It is well known that milk is a valuable source of many nutrients such as high-quality protein, calcium, vitamin D, magnesium, etc. ( 26 ). The most common stone phenotype is calcium-based, and the pathogenesis of kidney stones may be associated with metabolic pathways of calcium and vitamin D ( 13 ). However, studies on the relationship between the two and kidney stones are controversial ( 27 ). Previously, numerous prospective studies have indicated a strong correlation between increased dietary calcium intake and a decreased risk of kidney stones, a trend that is in line with our own findings ( 14 – 18 ). Among these studies, Borghi et al. observed that individuals with higher dietary calcium intake experienced a decrease in daily urinary oxalate excretion, thereby significantly lowering the likelihood of calcium oxalate stone formation ( 16 ). This phenomenon is attributed to the ability of dietary calcium to bind with dietary oxalates in the gastrointestinal tract, thereby reducing the absorption of oxalates and subsequent excretion in urine ( 28 ). Consequently, various organizations worldwide have consistently recommended that individuals with calcium stones ensure adequate dietary calcium intake, typically within the range of 1,000–1,200 mg daily ( 6 ). Moreover, balanced dietary calcium intake is advocated as a preventive measure against kidney stone formation ( 14 ). However, it is concerning that approximately 80% of the population does not meet the recommended dietary calcium intake established by the Institute of Medicine, which may further elevate the risk of developing kidney stones ( 18 ). Given that milk serves as a rich dietary source of calcium, our study suggests that maintaining a daily or more frequent milk consumption habit to some extent could help prevent the occurrence of kidney stones.

However, it is intriguing that Curhan et al. found that additional intake of calcium supplements could increase the risk of kidney stone formation ( 17 ). Randomized trial results have also indicated that daily supplementation with 1,000 mg of calcium carbonate and 400 IU of vitamin D may predispose individuals to kidney stones compared to a placebo ( 29 ). Notably, in this study, nearly two-thirds of participants took supplements between meals. Research has shown that when calcium supplements are taken with meals, they reduce the excretion of urinary oxalates ( 30 ). Hence, it can be speculated that the timing of calcium supplement intake, whether with meals or between meals, may have varying effects on the risk of kidney stone formation. Goldfarb suggests that the incidence of kidney stones may be lower if calcium supplements are administered in the form of citrate rather than carbonate. Regardless of whether the goal is to maintain bone density or prevent stone formation, dietary sources of calcium should be preferred over medications ( 31 ). The notable protective effect of dietary calcium against kidney stones may also be attributed to other dietary substances that could reduce the risk of stone formation. For instance, milk is rich in vitamin D, which enhances calcium absorption in the intestine. However, current prospective studies have indicated that vitamin D alone does not significantly affect the risk of kidney stones or hypercalcemia ( 32 , 33 ). Indeed, considering that most individuals do not meet the recommended daily dietary calcium intake according to guideline recommendations ( 18 ), it may pose a challenge to discern the impact of vitamin D on promoting calcium absorption. Therefore, it’s essential to consider an individual’s calcium and vitamin D concentrations before opting for additional calcium intake and vitamin D supplementation.

Increasing fluid intake is a well-established and long-standing recommendation for the prevention of kidney stones ( 6 ). Research has indicated a correlation between the consumption of beverages such as coffee, tea, and alcohol in daily life and a reduced risk of kidney stone formation ( 34 , 35 ). Furthermore, previous studies have suggested that milk consumption may alleviate the production of oxidative stress and inflammation ( 36 , 37 ), both recognized as pivotal factors in the etiology of kidney stones ( 38 ). Studies have reported a close association between elevated blood lipids and an increased risk of kidney stone incidence ( 39 ), with our research demonstrating a more pronounced reduction in the risk of kidney stone occurrence correlating with higher levels of milk fat removal. Therefore, given milk’s acknowledged status as a healthful beverage, we strongly advocate for the consumption of at least one or more servings of low-fat milk daily to mitigate the occurrence of kidney stones.

In subgroup analyses, we observed sex differences ( P for interaction = 0.033). Specifically, women may constitute the responsive group for increasing milk consumption to lower the risk of kidney stones (OR = 0.86, 95% CI 0.80–0.92), whereas men did not show a significant association (OR = 0.94, 95% CI 0.86–1.02). Presently, there is no evident explanation for this observation, suggesting the need for further investigation in future studies. Additionally, we identified a non-linear relationship between the prevalence of kidney stones and age in females using a smooth-fitting curve. Prior to menopause, the prevalence of kidney stones in women increased with age until menopause onset. This finding is consistent with conclusions from previous studies ( 40 , 41 ) and may be linked to decreased estrogen levels in women ( 42 ). Research has indicated that women undergoing estrogen replacement therapy exhibit elevated urinary citrate levels and enhanced coagulation inhibition, potentially reducing the risk of kidney stone formation ( 43 ). However, postmenopausal women experience a gradual decrease in the prevalence of kidney stones with advancing age, a trend not reported in earlier studies ( 40 – 42 ). Surprisingly, postmenopausal women using hormone replacement therapy showed a higher tendency for kidney stone development compared to non-users, although statistical significance was lacking ( 40 , 41 ). The current body of research cannot explain this observation, suggesting the necessity for further studies to elucidate the role of estrogen in postmenopausal women and associated mechanisms.

Furthermore, we observe an intriguing phenomenon in Figure 3D . Women who regularly consume milk exhibit a reversal of age-related changes in prevalence, maintaining a lower prevalence across all age ranges. We hypothesize that this observation may be linked to the magnesium content of milk. Hypomagnesuria is recognized as one of the known risk factors for kidney stone formation ( 6 ), and studies have demonstrated significantly lower 24-h urinary magnesium levels in postmenopausal women compared to premenopausal women ( 44 ). As the body ages, magnesium levels naturally decline. Magnesium deficiency has been associated with increased production of free radicals, consequently promoting oxidative stress and chronic inflammation ( 45 ), closely linked to the development of kidney stones ( 19 ). Adults are recommended to consume 320–420 mg of magnesium per day, and a single cup (234 ml) of low-fat milk contains approximately 33 mg of magnesium ( 46 ). Therefore, we underscore the importance of milk consumption, particularly advocating for the selection of low-fat milk, which may play a pivotal role in kidney stone prevention.

Our research presents several strengths. Firstly, it stands as the pioneering study to comprehensively evaluate the correlation between milk consumption and kidney stones. Secondly, our study incorporates extensive population data, considering complex sampling designs and weights to mitigate bias from oversampling, thereby ensuring the representativeness of the national population characteristics. Moreover, we adjust numerous covariates to enhance the accuracy of statistical analysis. Lastly, we conducted subgroup analyses to verify the stability of our results. Additionally, we plotted a smooth fitting curve, revealing the distinctive impact of milk consumption on kidney stone occurrence with advancing age. However, several limitations exist in this article. Firstly, the study’s cross-sectional design precludes establishing a cause-and-effect relationship. Secondly, reliance on self-reported data for both milk consumption and history of kidney stones introduces potential recall bias. Finally, there may be unobserved confounding factors, such as other types of dairy products or the influence of dietary calcium and other trace elements present in non-milk consumption sources. Due to limited data availability, these factors were not considered in our analysis. In future studies, it may be necessary to account for these potential confounders to ensure the rigor of the research conclusions.

5 Conclusion

Our research found that frequent milk consumption among women of all ages was linked to reduced rates of kidney stones. This discovery holds significant potential for public health interventions aimed at kidney stone prevention in women. However, due to the inherent limitations of cross-sectional studies, the robustness of this relationship is likely constrained and thus warrants validation through additional large prospective cohort studies.

Data availability statement

The original contributions presented in the study are included in the article/supplementary material, further inquiries can be directed to the corresponding author/s.

Ethics statement

All NHANES participants offered written informed consent, in alignment with the endorsement of the National Center for Health Statistics Research Ethics Review Board. The studies were conducted in accordance with the local legislation and institutional requirements. Written informed consent for participation in this study was provided by the participants’ legal guardians/next of kin.

Author contributions

ZX: Writing – original draft, Writing – review & editing, Conceptualization, Data curation, Formal analysis, Software, Visualization. YZ: Conceptualization, Writing – original draft, Writing – review & editing. SP: Writing – original draft, Writing – review & editing. XZ: Writing – original draft, Writing – review & editing. GZ: Writing – original draft, Writing – review & editing. HJ: Writing – original draft, Writing – review & editing. CZ: Conceptualization, Funding acquisition, Supervision, Writing – original draft, Writing – review & editing. NC: Conceptualization, Funding acquisition, Supervision, Writing – original draft, Writing – review & editing.

The author(s) declare that financial support was received for the research, authorship, and/or publication of this article. This study was supported by Natural Science Foundation of Guangdong Province – General Project (No. 2020A1515010015), Social Development Technology Plan Project of Meizhou City (No. 2020B090).

Acknowledgments

We sincerely thank all NHANES participants and the NHANES team for their invaluable contributions and dedication. We sincerely appreciate Changzhong Chen, Chi Chen, and Xing-Lin Chen (EmpowerStats X&Y Solutions, Inc., Boston, MA, USA) for providing statistical methodology consultation.

Conflict of interest

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Publisher’s note

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.

1. ^ https://www.cdc.gov/nchs/nhanes

2. ^ http://www.r-project.org/

3. ^ http://www.empowerstats.com

1. Rule, AD, Lieske, JC, and Pais, VM. Management of Kidney Stones in 2020. JAMA . (2020) 323:1961–2. doi: 10.1001/jama.2020.0662

Crossref Full Text | Google Scholar

2. Alexander, RT, Hemmelgarn, BR, Wiebe, N, Bello, A, Morgan, C, Samuel, S, et al. Kidney stones and kidney function loss: a cohort study. BMJ . (2012) 345:e5287. doi: 10.1136/bmj.e5287

PubMed Abstract | Crossref Full Text | Google Scholar

3. Romero, V, Akpinar, H, and Assimos, DG. Kidney stones: a global picture of prevalence, incidence, and associated risk factors. Rev Urol . (2010) 12:e86–96.

Google Scholar

4. Hill, AJ, Basourakos, SP, Lewicki, P, Wu, X, Arenas-Gallo, C, Chuang, D, et al. Incidence of kidney stones in the United States: the continuous National Health and nutrition examination survey. J Urol . (2022) 207:851–6. doi: 10.1097/JU.0000000000002331

5. Antonelli, JA, Maalouf, NM, Pearle, MS, and Lotan, Y. Use of the National Health and nutrition examination survey to calculate the impact of obesity and diabetes on cost and prevalence of urolithiasis in 2030. Eur Urol . (2014) 66:724–9. doi: 10.1016/j.eururo.2014.06.036

6. Peerapen, P, and Thongboonkerd, V. Kidney stone prevention. Adv Nutr . (2023) 14:555–69. doi: 10.1016/j.advnut.2023.03.002

7. Ferraro, PM, Bargagli, M, Trinchieri, A, and Gambaro, G. Risk of kidney stones: influence of dietary factors, dietary patterns, and vegetarian-vegan diets. Nutrients . (2020) 12. doi: 10.3390/nu12030779

8. Pereira, PC . Milk nutritional composition and its role in human health. Nutrition . (2014) 30:619–27. doi: 10.1016/j.nut.2013.10.011

9. Kliem, KE, and Givens, DI. Dairy products in the food chain: their impact on health. Annu Rev Food Sci Technol . (2011) 2:21–36. doi: 10.1146/annurev-food-022510-133734

10. Pratelli, G, Tamburini, B, Badami, GD, Lo Pizzo, M, De Blasio, A, Carlisi, D, et al. Cow's Milk: a benefit for human health? Omics tools and precision nutrition for lactose intolerance management. Nutrients . (2024) 16. doi: 10.3390/nu16020320

11. Willett, WC, and Ludwig, DS. Milk and health. N Engl J Med . (2020) 382:644–54. doi: 10.1056/NEJMra1903547

12. Luo, K, Chen, G-C, Zhang, Y, Moon, J-Y, Xing, J, Peters, BA, et al. Variant of the lactase Lct gene explains association between Milk intake and incident type 2 diabetes. Nat Metab . (2024) 6:169–86. doi: 10.1038/s42255-023-00961-1

13. Howles, SA, and Thakker, RV. Genetics of kidney stone disease. Nat Rev Urol . (2020) 17:407–21. doi: 10.1038/s41585-020-0332-x

14. Taylor, EN, and Curhan, GC. Dietary calcium from dairy and nondairy sources, and risk of symptomatic kidney stones. J Urol . (2013) 190:1255–9. doi: 10.1016/j.juro.2013.03.074

15. Curhan, GC, Willett, WC, Rimm, EB, and Stampfer, MJ. A prospective study of dietary calcium and other nutrients and the risk of symptomatic kidney stones. N Engl J Med . (1993) 328:833–8. doi: 10.1056/NEJM199303253281203

16. Borghi, L, Schianchi, T, Meschi, T, Guerra, A, Allegri, F, Maggiore, U, et al. Comparison of two diets for the prevention of recurrent stones in idiopathic Hypercalciuria. N Engl J Med . (2002) 346:77–84. doi: 10.1056/NEJMoa010369

17. Curhan, GC, Willett, WC, Speizer, FE, Spiegelman, D, and Stampfer, MJ. Comparison of dietary calcium with supplemental calcium and other nutrients as factors affecting the risk for kidney stones in women. Ann Intern Med . (1997) 126:497–504. doi: 10.7326/0003-4819-126-7-199704010-00001

18. Sorensen, MD, Kahn, AJ, Reiner, AP, Tseng, TY, Shikany, JM, Wallace, RB, et al. Impact of nutritional factors on incident kidney stone formation: a report from the WHI OS. J Urol . (2012) 187:1645–50. doi: 10.1016/j.juro.2011.12.077

19. Wu, J, Yang, Z, Wei, J, Zeng, C, Wang, Y, and Yang, T. Association between serum magnesium and the prevalence of kidney stones: a cross-sectional study. Biol Trace Elem Res . (2020) 195:20–6. doi: 10.1007/s12011-019-01830-3

20. Taylor, EN, Fung, TT, and Curhan, GC. Dash-style diet associates with reduced risk for kidney stones. J Am Soc Nephrol . (2009) 20:2253–9. doi: 10.1681/ASN.2009030276

21. Scales, CD, Smith, AC, Hanley, JM, and Saigal, CS. Prevalence of kidney stones in the United States. Eur Urol . (2012) 62:160–5. doi: 10.1016/j.eururo.2012.03.052

22. Lin, W, Ye, Q, and Lin, M-E. Relationship between the weight-adjusted-waist index and kidney stone: a population-based study. World J Urol . (2023) 41:3141–7. doi: 10.1007/s00345-023-04620-8

23. Marrie, RA, Dawson, NV, and Garland, A. Quantile regression and restricted cubic splines are useful for exploring relationships between continuous variables. J Clin Epidemiol . (2009) 62:511–517.e1. doi: 10.1016/j.jclinepi.2008.05.015

24. Park, S-Y, Freedman, ND, Haiman, CA, Le Marchand, L, Wilkens, LR, and Setiawan, VW. Association of Coffee Consumption with Total and cause-specific mortality among nonwhite populations. Ann Intern Med . (2017) 167:228–35. doi: 10.7326/M16-2472

25. Liu, S, Wang, X, Lu, Y, Li, T, Gong, Z, Sheng, T, et al. The effects of intraoperative cryoprecipitate transfusion on acute renal failure following orthotropic liver transplantation. Hepatol Int . (2013) 7:901–9. doi: 10.1007/s12072-013-9457-9

26. Misselwitz, B, Butter, M, Verbeke, K, and Fox, MR. Update on lactose malabsorption and intolerance: pathogenesis. Diagnosis Clin Manag Gut . (2019) 68:2080–91. doi: 10.1136/gutjnl-2019-318404

27. Messa, P, Castellano, G, Vettoretti, S, Alfieri, CM, Giannese, D, Panichi, V, et al. Vitamin D and calcium supplementation and urolithiasis: a controversial and multifaceted relationship. Nutrients . (2023) 15. doi: 10.3390/nu15071724

28. Hess, B, Jost, C, Zipperle, L, Takkinen, R, and Jaeger, P. High-calcium intake abolishes hyperoxaluria and reduces urinary crystallization during a 20-fold Normal oxalate load in humans. Nephrol Dial Transplant . (1998) 13:2241–7. doi: 10.1093/ndt/13.9.2241

29. Jackson, RD, LaCroix, AZ, Gass, M, Wallace, RB, Robbins, J, Lewis, CE, et al. Calcium plus vitamin D supplementation and the risk of fractures. N Engl J Med . (2006) 354:669–83. doi: 10.1056/NEJMoa055218

30. Domrongkitchaiporn, S, Sopassathit, W, Stitchantrakul, W, Prapaipanich, S, Ingsathit, A, and Rajatanavin, R. Schedule of taking calcium supplement and the risk of nephrolithiasis. Kidney Int . (2004) 65:1835–41. doi: 10.1111/j.1523-1755.2004.00587.x

31. Goldfarb, DS . Does vitamin D supplementation cause kidney stones? J Urol . (2017) 197:280–1. doi: 10.1016/j.juro.2016.11.072

32. Ferraro, PM, Taylor, EN, Gambaro, G, and Curhan, GC. Vitamin D intake and the risk of incident kidney stones. J Urol . (2017) 197:405–10. doi: 10.1016/j.juro.2016.08.084

33. Malihi, Z, Lawes, CMM, Wu, Z, Huang, Y, Waayer, D, Toop, L, et al. Monthly high-dose vitamin D supplementation does not increase kidney stone risk or serum calcium: results from a randomized controlled trial. Am J Clin Nutr . (2019) 109:1578–87. doi: 10.1093/ajcn/nqy378

34. Ferraro, PM, Taylor, EN, Gambaro, G, and Curhan, GC. Soda and other beverages and the risk of kidney stones. Clin J Am Soc Nephrol . (2013) 8:1389–95. doi: 10.2215/CJN.11661112

35. Littlejohns, TJ, Neal, NL, Bradbury, KE, Heers, H, Allen, NE, and Turney, BW. Fluid intake and dietary factors and the risk of incident kidney stones in Uk biobank: a population-based prospective cohort study. Eur Urol Focus . (2020) 6:752–61. doi: 10.1016/j.euf.2019.05.002

36. Zemel, MB, Sun, X, Sobhani, T, and Wilson, B. Effects of dairy compared with soy on oxidative and inflammatory stress in overweight and obese subjects. Am J Clin Nutr . (2010) 91:16–22. doi: 10.3945/ajcn.2009.28468

37. Stancliffe, RA, Thorpe, T, and Zemel, MB. Dairy Attentuates oxidative and inflammatory stress in metabolic syndrome. Am J Clin Nutr . (2011) 94:422–30. doi: 10.3945/ajcn.111.013342

38. Liu, C-C, Hsieh, T-J, Wu, C-F, Lee, C-H, Tsai, Y-C, Huang, T-Y, et al. Interrelationship of environmental melamine exposure, biomarkers of oxidative stress and early kidney injury. J Hazard Mater . (2020) 396:122726. doi: 10.1016/j.jhazmat.2020.122726

39. Hung, J-A, Li, C-H, Geng, J-H, Wu, D-W, and Chen, S-C. Dyslipidemia increases the risk of incident kidney stone disease in a large Taiwanese population follow-up study. Nutrients . (2022) 14:7. doi: 10.3390/nu14071339

40. Prochaska, M, Taylor, EN, and Curhan, G. Menopause and risk of kidney stones. J Urol . (2018) 200:823–8. doi: 10.1016/j.juro.2018.04.080

41. Tang, T-Y, Lee, J-I, Shen, J-T, Lee, Y-C, Wang, H-S, Tsao, Y-H, et al. The association between menopause, postmenopausal hormone therapy, and kidney stone disease in Taiwanese women. Ann Epidemiol . (2023) 78:13–8. doi: 10.1016/j.annepidem.2022.12.002

42. Nackeeran, S, Katz, J, Ramasamy, R, and Marcovich, R. Association between sex hormones and kidney stones: analysis of the National Health and nutrition examination survey. World J Urol . (2021) 39:1269–75. doi: 10.1007/s00345-020-03286-w

43. Dey, J, Creighton, A, Lindberg, JS, Fuselier, HA, Kok, DJ, Cole, FE, et al. Estrogen replacement increased the citrate and calcium excretion rates in postmenopausal women with recurrent urolithiasis. J Urol . (2002) 167:169–71. doi: 10.1016/S0022-5347(05)65405-5

44. Mai, Z, Li, X, Jiang, C, Liu, Y, Chen, Y, Wu, W, et al. Comparison of metabolic changes for stone risks in 24-hour urine between non- and postmenopausal women. PLoS One . (2019) 14:e0208893. doi: 10.1371/journal.pone.0208893

45. Barbagallo, M, Veronese, N, and Dominguez, LJ. Magnesium in aging, health and diseases. Nutrients . (2021) 13:2. doi: 10.3390/nu13020463

46. Volpe, SL . Magnesium in disease prevention and overall health. Adv Nutr . (2013) 4:378S–83S. doi: 10.3945/an.112.003483

Keywords: milk consumption, kidney stones, NHANES, cross-sectional study, female

Citation: Xie Z, Zhuang Y, Peng S, Zhou X, Zhang G, Jiang H, Zhang C and Chen N (2024) Association between milk consumption and kidney stones in U.S. adults: results from NHANES 2007–2018. Front. Nutr . 11:1394618. doi: 10.3389/fnut.2024.1394618

Received: 01 March 2024; Accepted: 06 May 2024; Published: 15 May 2024.

Reviewed by:

Copyright © 2024 Xie, Zhuang, Peng, Zhou, Zhang, Jiang, Zhang and Chen. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY) . The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

*Correspondence: Changyi Zhang, [email protected] ; Nanhui Chen, [email protected]