Conditions: Formalized Case Selection for Process Tracing after QCA

This paper aims at strengthening causal inference in necessary condition research. We demonstrate how process tracing based on purposefully selected cases can complement findings on cross-case patterns identified with Qualitative Comparative Analysis (QCA). Using an empirical example, we discuss the meaning of typical and deviant cases in analyses of necessity, develop formulas for identifying the most typical and most deviant cases, and detail the implications of so-called SUIN conditions for meaningful case selection. In addition, we clarify various viable variants of comparative process tracing and formulas for identifying the best-matching pairs of cases.