Assessing the Robustness of Crisp-set and Fuzzy-set QCA Results

Configurational comparative methods constitute promising methodological tools that narrow the gap between variable-oriented and case-oriented research. Their infancy, however, means that the limits and advantages of these techniques are not clear. Tests on the sensitivity of qualitative comparative analysis (QCA) results have been sparse in previous empirical studies, and so has the provision of guidelines for doing this. Therefore this article uses data from a textbook example to discuss and illustrate various robustness checks of results based on the employment of crisp-set QCA and fuzzy-set QCA. In doing so, it focuses on three issues: the calibration of raw data into set-membership values, the frequency of cases linked to the configurations, and the choice of consistency thresholds. The study emphasizes that robustness tests, using systematic procedures, should be regarded as an important, and maybe even indispensable, analytical step in configurational comparative analysis.