This paper is a systematic analysis of the comparative method. Its emphasis is on both the limitations of the method and the ways in which, despite these limitations, it can be used to maximum advantage.
The comparative method is defined and analyzed in terms of its similarities and differences vis-à-vis the experimental and statistical methods. The principal difficulty facing the comparative method is that it must generalize on the basis of relatively few empirical cases. Four specific ways in which this difficulty may be resolved are discussed and illustrated: (1) increasing the number of cases as much as possible by means of longitudinal extension and a global range of analysis, (2) reducing the property space of the analysis, (3) focusing the comparative analysis on “comparable” cases (e.g., by means of area, diachronic, or intranation comparisons), and (4) focusing on the key variables.
It is argued that the case study method is closely related to the comparative method. Six types of case studies (the atheoretical, interpretative, hypothesis-generating, theory-confirming, theory-infirming, and deviant case analyses) are distinguished, and their theoretical value is analyzed.