2. Case Study Methods: Design, Use, and Comparative Advantages

There is a growing consensus among social scientists that research programs advance more effectively through the iterative or collaborative use of different research methods than through the use of any one method alone. Making the most of the synergies among research methods requires an understanding of the relative comparative advantages, trade-offs, and limitations of each method and an ability to translate between different methods. The comparative advantages of case study methods include identifying new or omitted variables and hypotheses, examining intervening variables in individual cases to make inferences on which causal mechanisms may have been at work, developing historical explanations of particular cases, attaining high levels of construct validity, and using contingent generalizations to model complex relationships such as path dependency and multiple interactions effects. Particularly important is the ability to identify new hypotheses, which case studies can do through a combination of deduction and induction. Recurrent trade-offs in the use of case study methods include the problem of case selection and the danger of selection bias, which can have more severe consequences in case studies than in statistical studies, and the tension between parsimony and richness in selecting the number of variables and cases to be studied. In addition, case study ‹ndings are usually contingent and can be generalized beyond the type of case studied only under speci‹ed conditions, such as when a case study shows that a variable is not