Political scientist Cammett considers the use of positive deviant cases – examples of sustained high performance in a context in which good results are uncommon – to identify and disentangle causal complexity and understand the role of context. Although the consensus view on the role of deviant cases is that they are most useful for exploratory purposes or discovery and theory building, Cammett suggests they can also generate insights into the identification and operation of causal mechanisms. She writes that “analyses of positive deviant cases among a field of otherwise similar cases that operate in the same context … can be a valuable way to identify potential explanatory variables for exceptional performance.” The hypothesized explanatory variables can then be incorporated in subsequent quantitative or qualitative studies in order to evaluate their effects across a broader range of observations. The chapter discusses how to approach selection of positive deviant cases systematically and then works through a real example.

It significantly strengthens the inferences drawn based on QCA results if we connect these results to theoretical knowledge and within-case evidence before, during, and after the analysis. In this chapter, we discuss two prominent tools of doing so after the analytic moment – set-theoretic theory evaluation and set-theoretic multi-method research (SMMR) – and demonstrate their implementation within R. Theory evaluation is a form of re-assessing theoretical hunches based on the results generated by QCA. While it can also be used for the identification of interesting cases for follow-up case studies, this task is better achieved with set-theoretic multi-method research. The latter is a tool for identifying typical and deviant cases for comparative or single within-case analysis.

Learning goals:

- Basic understanding of what theory-evaluation and set-theoretic multimethod research are.

- Familiarity with how to apply formal set-theoretic theory evaluation for re-assessing theoretical hunches based on the results generated by QCA.

- Familiarity with how to use set-theoretic multi-method research (SMMR) for the identification of cases for follow-up case studies after QCA.

- Ability to implement theory evaluation and SMMR in R.