Comparative Methods

At the most general level, the term comparative methods may be used to refer to any research technique that focuses on patterns of similarities and differences across cases. More commonly, however, the term is used to refer to a family of techniques employed by small-N researchers. It is this family of techniques that is the main focus of this entry. Though comparative methods do have particular advantages for small-N researchers, there is no inherent connection between comparative methods and small Ns. The development of formal methods of comparative research—specifically, qualitative comparative analysis (QCA) and related techniques—has facilitated the extension of comparative logic, which is configurational in nature, to large-N studies.

This entry has six major sections. The first emphasizes the case-oriented nature of comparative research. This feature clearly differentiates it [Page 332]from conventional variable-oriented research and underscores its broad links to qualitative inquiry in general. The second section considers the goals of comparative research, linking comparative research to both inductive theory building and deductive theory testing. The logic of comparative analysis is the central focus of the third section. The importance of the analysis of set-theoretic relations to comparative research is emphasized, and the analysis of sufficiency and necessity is linked to subset and superset relations. These connections are important because much of social science theory is formulated in terms of set relations, and it is important to use analytic methods that are true to theoretical formulations. The language and logic of sets underlie both informal and formal methods of comparative analysis, which is the topic of the fourth section. Traditionally, comparative researchers have made use of informal methods, explicitly or implicitly relying on John Stuart Mill's methods of agreement and difference. Over the past 2 decades, Charles Ragin has formalized the comparative method as QCA, which is discussed in detail in this section. In the fifth section, discontinuities between comparative research and conventional variable-oriented research are addressed, and in the closing section, current development in formal methods of comparative analysis is described.