Causal-Comparative Research

Alternative to Experimental Research

Causal-comparative research is an alternative to experimental and quasi-experimental designs, but the distinction with experimental research is an important one. In general, experimental designs involve some manipulation by the researcher of a causal intervention or treatment of some kind. For the so-called true experiments, the distinction with causal-comparative research is readily apparent: A true experiment has random assignment of participants to an experimental condition. The distinction with quasi-experimental research may be less obvious in certain cases. In some quasi-experimental studies, the researcher may work with intact groups just as in causal-comparative research, but a quasi-experiment would have a manipulation of some kind. By contrast, in causal-comparative research, the researcher does not control the study conditions.

Consider the following example: A researcher studying the potential causes for observed differences in elementary classes’ average mathematics achievement chooses to focus on use of newer textbooks in some of the classes. In this example, the effect is the difference in mathematics achievement, and the potential cause is the use of the new textbook. The two groups to be compared are classes using the newer textbooks and classes using the older textbooks. In a true experiment, the researcher would form groups by randomly assigning students into classes using the new textbooks or an older textbook. In a quasi-experiment, the researcher would not be able to assign the students into classes randomly but may still be able to [Page 252]assign some classes to use the new textbook as a comparison with classes using the older textbook. In a causal-comparative study, the researcher does not assign students to classes and does not influence which textbooks are used. Instead, the researcher finds classes already using the new textbook and compares them with classes using the older textbook.

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