Case-to-Condition Ratios in Qualitative Comparative Analysis: Adding Cases Instead of Removing Conditions

Abstract

In qualitative comparative analysis, as with all methods, there is a question about how many cases are needed to make an analysis robust. In deciding on the number of cases, a key consideration is the number of conditions to be analyzed. I suggest that adding cases is preferable to dropping conditions if there are too many conditions relative to the number of cases. I first consider the relationship of low n and limited diversity, followed by an exploration of two scenarios: (1) cases in the study are the universe; (2) more cases could exist. I suggest that a simple rule or benchmark on how many cases to include in relation to the number of conditions is unlikely to be helpful since this depends at least in part on the goals and circumstances of the research. Finally, this issue is not confined to QCA but affects all types of research.