Case Studies and Theory Development in the Social Sciences - Alexander L. George [44]
• What exactly and precisely is the dependent (or outcome) variable to be explained or predicted?
• What independent (and intervening) variables comprise the theoretical framework of the study?
• Which of these variables will be held constant (serve as parameters) and which will vary across cases included in the comparison?
The specification of the problem in Task One is closely related to the statement of what exactly the dependent variable will be. If a researcher defines the problem too broadly, he or she risks losing important differences among cases being compared. If a researcher defines the problem too narrowly, this may severely limit the scope and relevance of the study and the comparability of the case findings.169 As will be noted, the definition of variance in the dependent variable is critical in research design.
In analyzing the phenomenon of “war termination,” for instance, a researcher would specify numerous variables. The investigator would decide whether the dependent (outcome) variable to be explained (or predicted) was merely a cease-fire or a settlement of outstanding issues over which the war had been fought. Variables to be considered in explaining the success or failure of war termination might include the fighting capabilities and morale of the armed forces, the availability of economic resources for continuing the war, the type and magnitude of pressures from more powerful allies, policymakers’ expectation that the original war aim was no longer attainable at all or only at excessive cost, the pressures of pro-war and anti-war opinion at home, and so on. The researcher might choose to focus on the outcome of the dependent variable (e.g., on cases in which efforts to achieve a cease-fire or settlement failed, but adding cases of successful cease-fires or settlements for contrast) to better identify the independent and intervening variables associated with such failures. Alternatively, one might vary the outcome, choosing cases of both successes and failures in order to identify the conditions and variables that seem to account for differences in outcomes.
Alternatively, the research objective may focus not on outcomes of the dependent variable, but on the importance of an independent variable—e. g., war weariness—in shaping outcomes in a number of cases.
We conclude this discussion of Task Two with a brief review of the strengths and weaknesses of the common types of case study research designs in relation to the kinds of research objectives noted above.
First, single case research designs can fall prey to selection bias or over-generalization of results, but all of the six theory-building purposes identified above have been served by studies of single well-selected cases that have avoided or minimized such pitfalls. Obviously, single-case studies rely almost exclusively on within-case methods, process-tracing, and congruence, but they may also make use of counterfactual analysis to posit a control case.170
For theory testing in single cases, it is imperative that the process-tracing procedure and congruence tests be applied to a wide range of alternative hypotheses that theorists and even participants in the events have proposed, not only to the main hypotheses of greatest interest to the researcher. Otherwise, left-out variables may threaten the validity of the research design. Single cases serve the purpose of theory testing particularly well if they are “most-likely,” “least-likely,” or “crucial” cases. Prominent case studies by Arend Lijphart, William Allen, and Peter Gourevitch, for example, have changed entire research programs by impugning theories that failed to explain their most-likely cases.171
Similarly, studies of single “deviant” cases and of single