The following module contains a discussion of the benefits and limitations of using comparative research methods.

Learning Objectives

• Describe the benefits or advantages of comparative research methods
• Describe the limitations or disadvantages of comparative research methods

Comparative research is studying two or more similar groups, individuals, countries, events or conditions by comparing them with respect to specific characteristics. Through such comparisons, comparative research offers a mechanism to understand and evaluate the factors that shape and change our world. It can provide insight into world events, a greater understanding of the governments and systems that exist throughout the world, a means for learning from past mistakes, and a greater understanding of other cultures. To some extent, all research is comparative in nature and comparative research offers many benefits and advantages. However, as with all types of research, it has limitations as well. Following is a summary of the benefits and limitations of comparative research.

Benefits of Comparative Research

• It may help to identify causes or explanations for existing conditions or historical events.
• It uses existing groups or cases and thereby simplifies some steps of the research process. Since it focuses on the differences and similarities, the cases or groups are typically drawn from a known or predetermined set.
• Variables are not manipulated, and treatments are not applied, again simplifying steps of the research process. In comparative research, the effect of the variable has already occurred, and the goal is to examine the impact or effect of the independent variable on the dependent variable. It is a commonly chosen method when variables cannot be manipulated due to ethical or practical reasons.
• Most of the data is collected from already existing sources, reducing procedural efforts and many of the ethical concerns.
• Often a wealth of existing information available to use as data.
• Less costly than most experimental studies.
• Careful selection of groups or cases that are homogeneous with respect to the extraneous variables helps to ensure the reliability of the findings by removing influence of extraneous variables.
• The analytic frame, mentioned in previous modules, can be flexible and modified as the research progresses. The flexibility makes the comparative method a good strategy for advancing theory.
• Comparative research facilitates the understanding of historical events because it focuses on the differences between cases and events the differentiation often leads to greater insight.
• These types of studies often bring together researchers from different backgrounds and disciplines.

Limitations of Comparative Research

• It may sometimes be difficult to find the same types of data for the groups or cases for making a true comparison.
• The accuracy and source of the data may need to be evaluated and verified to ensure reliable findings.
• Only true experimental research can definitively determine cause-effect relationships. Findings from comparative research should be reported as showing a “possible effect” or a “possible cause”.
• There can be several reasons why variables are related to each other and may be difficult to pinpoint the exact reason.
• Groups or cases must be carefully chosen to control for extraneous variables. It is best to ensure that the groups or cases are similar in regard to extraneous variables to reduce their potential impact.
• The groups or cases are chosen from a predetermined subset and not selected randomly. This negatively impacts the ability of the research to generalize the findings.
• Especially when working with a cross-national comparative study, gaining access to comparable data may be an issue. For some cases, the comparable data from a particular country may not exist or may have been destroyed. It may be necessary to form an international team comprised of members from all countries involved to gain access to the needed information. There can be many problems and challenges associated with building a managing such a team.
• Language barriers may be an issue in cross-national studies.
• Comparative research requires that the research make presumption that the independent variable has the same consequence every time.
• In some cases, the direction of causality may be disputed and must be considered by the researcher. Comparative studies also do not account for situations where multiple causation is possible.
• The correct classification of events, cases, groups, or individuals into categories for comparison is a key concern in the comparative method because the classifications developed determine the subsets from which cases or groups are drawn for comparisons.

Suggested Readings

Collier, D. (1993). The comparative method. Political Science: The State of Discipline II, Ada W. Finifter, ed., American Political Science Association.
Geddes, B. (2003). Paradigms and sandcastles: Theory building and research design in comparative politics. University of Michigan Press.
Lijphart, A. (1971). Comparative politics and the comparative method. American political science review, 65(03), 682-693.
Lijphart, A. (1975). The comparable-cases strategy in comparative research. Comparative political studies, 8(2), 158.
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.