This module provides an introduction to the comparative method used in research.

 Learning Objectives

• Define and describe the comparative method
• Describe the use of the comparative method
• Provide examples of comparative research

Comparative researchers study cases looking for patterns of similarities and differences. Typically, a comparative study will examine anywhere from a handful to fifty or more cases that the researchers study in depth. The design of a comparative research study is relatively simple. The specimens or cases will be different in some regards and similar in other regards. The comparative method is design to focus on the differences and explore why the cases are different. It is a commonly used method in social science research when there are relatively few cases, but many variables in each case. It is method that often chosen when researchers are looking for patterns of diversity or differences among cases.

To a certain extent, all research is comparative in nature. However, the comparative method is different than the qualitative and quantitative methods previously discussed in other modules. The qualitative method focuses on the commonalities and similarities between the cases. The researcher may use the similarities to classify the cases into categories. Quantitative researchers are similar to comparative researchers in that the focus is on the differences among the cases. In quantitative research, though, the emphasis is on the differences in one of more variables across the cases. The comparative method focuses on the differences and variances between the cases themselves and seeks to explain those differences. Therefore, it is a considered to be a method that focuses on the diversity of the cases. The comparative method is sometimes described as falling between qualitative and quantitative research.

The goals of comparative research are to explore diversity, interpret cultural or historical significance and to advance theory. Following are some examples of comparatives studies with these goals in mind:

Exploring Diversity

• Studying the stability of non-democratic government across countries.
• Examining the causes of revolutions in third world countries.
• Examining quality of life indicators among members of different socioeconomic groups.

Interpreting Cultural or Historical Significance

• Studying countries that have experienced civil wars to gain a better historical understanding of how the wars begin.
• Studying attitudes towards welfare among people of different cultures.

Advancing Theory

• Examining the number of government welfare programs and comparing it among the states only to find there are more type of programs than originally anticipated.
• Studying the differences among cases to find the cause of the differences and thereby, advance understanding of a particular concept.

There are two main styles of comparative studies – descriptive comparisons and normative comparisons. Most studies are descriptive comparisons that are designed to describe, and often explain, the cases and the differences among them. Normative comparison studies are a special style of research that goes beyond simply describing the cases by using at least one “evaluative” criterion. The goal is to be able to provide the basis for change or improvement the cases or objects. Both styles compare cases by emphasizing the differences among the cases. 

There are several types of comparative research studies. The upcoming modules will focus on three of the most common types including cross-national comparisons, historical comparisons, and causal comparisons. The Resource Links on this page contain additional information about types of comparative research.

Suggested Readings

Collier, D. (1993). The comparative method.  Political Science: The State of Discipline II, Ada W. Finifter, ed., American Political Science Association .
Lijphart, A. (1971). Comparative politics and the comparative method. American political science review , 65 (03), 682-693.
Harvey, P. H., & Pagel, M. D. (1991). The comparative method in evolutionary biology (Vol. 239). Oxford: Oxford university press.
Pagel, M. D. (1992). A method for the analysis of comparative data. Journal of theoretical Biology , 156 (4), 431-442.
Ragin, C., & Zaret, D. (1983). Theory and method in comparative research: Two strategies. Social forces , 61 (3), 731-754.
Ragin, C. C. (2014). The comparative method: Moving beyond qualitative and quantitative strategies . Univ of California Press.
Van de Vijver, F., & Leung, K. (1997). Methods and data analysis of comparative research . Allyn & Bacon.