This chapter explores the methodological approaches that rely on a small number of case studies to examine political phenomena (i.e., small-n research). Two important and complementary research methods are singled out for examination: the case study and comparative research.
A case study is defined as a detailed analysis of a single discrete phenomenon—one that begins with the observation of a counter-intuitive. Two types of case studies—descriptive and theory testing—are then described in detail. The former is defined as a case study in which the researcher knows little or nothing about a phenomenon. The latter is appropriate if one of two distinct counter-intuitive conditions is met: a phenomenon is expected to confirm a theory but refutes it (the failed most-likely case) or a phenomenon is expected to refute a theory but confirms it (the successful least-likely case). This section also details the four factors to consider when evaluating a case study.
The chapter goes on to discuss comparative research design, which systematically contrasts a number of cases in order to create stronger generalizations. The two principal approaches to comparative research are most-similar-systems design (in which researchers compare very similar systems in an attempt to explain differences between them) and most-different-systems design (in which researchers compare very different systems in an attempt to explain similarities between them). The chapter concludes with a discussion of the issues researchers should consider when employing the comparative method.