comparative case study method

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Comparative Case Study

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A comparative case study (CCS) is defined as ‘the systematic comparison of two or more data points (“cases”) obtained through use of the case study method’ (Kaarbo and Beasley 1999, p. 372). A case may be a participant, an intervention site, a programme or a policy. Case studies have a long history in the social sciences, yet for a long time, they were treated with scepticism (Harrison et al. 2017). The advent of grounded theory in the 1960s led to a revival in the use of case-based approaches. From the early 1980s, the increase in case study research in the field of political sciences led to the integration of formal, statistical and narrative methods, as well as the use of empirical case selection and causal inference (George and Bennett 2005), which contributed to its methodological advancement. Now, as Harrison and colleagues (2017) note, CCS:

“Has grown in sophistication and is viewed as a valid form of inquiry to explore a broad scope of complex issues, particularly when human behavior and social interactions are central to understanding topics of interest.”

It is claimed that CCS can be applied to detect causal attribution and contribution when the use of a comparison or control group is not feasible (or not preferred). Comparing cases enables evaluators to tackle causal inference through assessing regularity (patterns) and/or by excluding other plausible explanations. In practical terms, CCS involves proposing, analysing and synthesising patterns (similarities and differences) across cases that share common objectives.

What is involved?

Goodrick (2014) outlines the steps to be taken in undertaking CCS.

Key evaluation questions and the purpose of the evaluation: The evaluator should explicitly articulate the adequacy and purpose of using CCS (guided by the evaluation questions) and define the primary interests. Formulating key evaluation questions allows the selection of appropriate cases to be used in the analysis.

Propositions based on the Theory of Change: Theories and hypotheses that are to be explored should be derived from the Theory of Change (or, alternatively, from previous research around the initiative, existing policy or programme documentation).

Case selection: Advocates for CCS approaches claim an important distinction between case-oriented small n studies and (most typically large n) statistical/variable-focused approaches in terms of the process of selecting cases: in case-based methods, selection is iterative and cannot rely on convenience and accessibility. ‘Initial’ cases should be identified in advance, but case selection may continue as evidence is gathered. Various case-selection criteria can be identified depending on the analytic purpose (Vogt et al., 2011). These may include:

• Very similar cases
• Very different cases
• Typical or representative cases
• Extreme or unusual cases
• Deviant or unexpected cases
• Influential or emblematic cases

Identify how evidence will be collected, analysed and synthesised: CCS often applies mixed methods.

Test alternative explanations for outcomes: Following the identification of patterns and relationships, the evaluator may wish to test the established propositions in a follow-up exploratory phase. Approaches applied here may involve triangulation, selecting contradicting cases or using an analytical approach such as Qualitative Comparative Analysis (QCA). Download a Comparative Case Study here Download a longer briefing on Comparative Case Studies here

Useful resources

A webinar shared by Better Evaluation with an overview of using CCS for evaluation.

A short overview describing how to apply CCS for evaluation:

Goodrick, D. (2014). Comparative Case Studies, Methodological Briefs: Impact Evaluation 9 , UNICEF Office of Research, Florence.

An extensively used book that provides a comprehensive critical examination of case-based methods:

Byrne, D. and Ragin, C. C. (2009). The Sage handbook of case-based methods . Sage Publications.

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Comparative case studies

Comparative case studies can be useful to check variation in program implementation. 

Comparative case studies are another way of checking if results match the program theory. Each context and environment is different. The comparative case study can help the evaluator check whether the program theory holds for each different context and environment. If implementation differs, the reasons and results can be recorded. The opposite is also true, similar patterns across sites can increase the confidence in results.

Evaluators used a comparative case study method for the National Cancer Institute’s (NCI’s) Community Cancer Centers Program (NCCCP). The aim of this program was to expand cancer research and deliver the latest, most advanced cancer care to a greater number of Americans in the communities in which they live via community hospitals. The evaluation examined each of the program components (listed below) at each program site. The six program components were:

• increasing capacity to collect biospecimens per NCI’s best practices;
• enhancing clinical trials (CT) research;
• reducing disparities across the cancer continuum;
• improving the use of information technology (IT) and electronic medical records (EMRs) to support improvements in research and care delivery;
• improving quality of cancer care and related areas, such as the development of integrated, multidisciplinary care teams; and
• placing greater emphasis on survivorship and palliative care.

The evaluators use of this method assisted in providing recommendations at the program level as well as to each specific program site.

Advice for choosing this method

• Compare cases with the same outcome but differences in an intervention (known as MDD, most different design)
• Compare cases with the same intervention but differences in outcomes (known as MSD, most similar design)

Advice for using this method

• Consider the variables of each case, and which cases can be matched for comparison.
• Provide the evaluator with as much detail and background on each case as possible. Provide advice on possible criteria for matching.

National Cancer Institute, (2007).  NCI Community Cancer Centers Program Evaluation (NCCCP) . Retrieved from website: https://digitalscholarship.unlv.edu/jhdrp/vol8/iss1/4/

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• Broadening the range of designs and methods for impact evaluations

'Comparative case studies' is referenced in:

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• Rainbow Framework :  Check the results are consistent with causal contribution
• Sustained and Emerging Impacts Evaluation (SEIE)

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A comparative study of 2D numerical simulations using vector and potential methods for extending 3D modeling of planetary evolution

• Published: 23 May 2024

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• Kyeong-Min Lee 1 ,
• Hyo-Im Kim 2 , 3 ,
• Deok-Kyu Jang 4 , 5 &
• Byung-Dal So 1  

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Numerical simulations provide an improved understanding of the evolution and core formation processes of terrestrial bodies. The differentiation of silicate and iron metal has been simulated by solving the two-dimensional Stokes equation using either the vector or potential method. To describe the realistic geometry of planetesimals and planets, the development of a 3D model is necessary. Here, we developed a vector method model implemented in FEniCS project via scripting the weak forms of governing equations. Subsequently, we compared the solutions of the vector method models with those of the benchmark potential method implemented in Python. Three cases were modeled using the two methods and confirmed for consistency to verify the feasibility of developing a 3D model for core formation. Case 1 corresponds to planetary evolution triggered by impact heating in early terrestrial bodies with a homogeneous metal fraction. The vector method developed in the current study showed the consistency with the potential methods. In Case 2, the model mimicked a scenario depicting post-evolutionary impact heating by assuming heterogeneous metal fractions. The results of Case 2 simultaneously represent the behavior of the solid mixture based on the density contrast and multiphase flow of the solid matrix and metallic pores. The checkerboard test (Case 3) used to evaluate the resolution of the numerical model as a function of the heat source size also indicated identical spatial resolutions for both methods. In all cases, two methods simulated identical physical behaviors, indicating that a three-dimensional model can be developed using the vector method. The 2D FEM vector method developed in this study was effectively utilized to simulate the advection scheme, showing the fast descent of metal phases and relatively slower silicate phases. We extended the 2D FEM vector method to calculate the velocity fields of silicate, Darcy, and iron metal in a 3D model with an impact heating case (similar to Case 1). The 3D results show that the velocity of fluid metal in 3D model is faster than that in 2D model, suggesting the difference in the resistance to viscous flow depending the dimension of model. Our 3D vector method, implemented in FEniCS, demonstrates the numerical prospect of the methods necessary to model the multiphase fluid dynamics of a 3D planetary evolution.

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Acknowledgments

This research was supported by the National Foundation of Korea (NRF) grants funded by the Ministry of Science and ICT of Korea (NRF-2022R1A4A3027001, NRF-2022R1A2C1009742, and NRF-2022R1C1C1003385). This work was also supported by the Korea Institute of Marine Science & Technology Promotion (KIMST) funded by the Ministry of Oceans and Fisheries (RS-2023-00259686). K.-M. Lee is supported by the Ministry of the Interior and Safety, as the Human Resource Development Project in Disaster Management.

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Department of Geophysics, Kangwon National University, Chuncheon, 24341, Republic of Korea

Kyeong-Min Lee & Byung-Dal So

Department of Geology, Gyeongsang National University, 501, Jinjudaero, Jinju, 52828, Republic of Korea

Research Institute of Molecular Alchemy, Gyeongsang National University, Jinju, 52828, Republic of Korea

Research Institute for Earth Resources, Kangwon National University, Chuncheon, 24341, Republic of Korea

Deok-Kyu Jang

Department of Mathematics, Kangwon National University, Chuncheon, 24341, Republic of Korea

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Lee, KM., Kim, HI., Jang, DK. et al. A comparative study of 2D numerical simulations using vector and potential methods for extending 3D modeling of planetary evolution. Geosci J (2024). https://doi.org/10.1007/s12303-024-0013-5

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Received : 02 January 2024

Accepted : 11 April 2024

Published : 23 May 2024

DOI : https://doi.org/10.1007/s12303-024-0013-5

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