Social scientists have a plethora of ways to gather information about group processes. To describe how groups operate, researchers can observe groups in action, examine archival data sources, and use interviews or questionnaires to ask individuals about their beliefs and motivations. All of these techniques are useful, but none allows firm statements about causality. For this reason, researchers often utilize experiments, which, if properly conducted, allow strong inferences about the factors that produce various group behaviors. Because of this ability, experimentation is the most widely used methodology in group research.

Experimentation involves the manipulation of one or more independent variables to investigate the effects on one or more dependent variables. Experimentation is a powerful method because it allows the researcher to draw causal explanations about the ...