Students as Experimental Participants: A Defense of the 'Narrow Data Base'
James N. Druckman
Northwestern University - Department of Political Science
Cindy D. Kam
Vanderbilt University - Department of Political Science
July 6, 2009
We investigate the extent to which using students as experimental participants creates problems for causal inference. First, we discuss the impact of student subjects on a study’s internal and external validity. In contrast to common claims, we argue that student subjects do not intrinsically pose a problem for a study’s external validity. Second, we use simulations to identify situations when student subjects are likely to constrain experimental inferences. We show that such situations are relatively limited; any convenience sample poses a problem only when the size of an experimental treatment effect depends upon a characteristic on which the convenience sample has virtually no variance. Third, we briefly survey empirical evidence that provides guidance on when researchers should be particularly attuned to taking steps to ensure appropriate generalizability from student subjects. We conclude with a discussion of the practical implications of our findings. In short, we argue that student subjects are not an inherent problem to experimental research; moreover, the burden of proof - of student subjects being a problem - should lie with critics rather than experimenters.
Number of Pages in PDF File: 34
Keywords: experiments, subjects, public opinion, methods
JEL Classification: C9
Date posted: November 3, 2009