Buster runs an experiment in which she finds that participants placed in a good mood by a happy film clip are more likely to offer help to a fellow participant than participants who see a sad film clip. Bob suggests that perhaps this difference simply results from the fact that the participants in the happy film clip condition were more helpful people to begin with. What methodological aspect of a successful experiment can Buster point to in order to refute this criticism?

Question

Quizplus · Accepted Answer

Random assignment is the methodological aspect that can help refute Bob's criticism. It ensures that any pre-existing differences among participants are evenly distributed across all experimental conditions, thus making it unlikely that the observed differences in helpfulness are due to the participants' inherent characteristics rather than the effect of the film clips.

Buster Runs an Experiment in Which She Finds That Participants