A group whose characteristics are similar to those of the program but who do not receive the program services, products, or activities being evaluated. Participants are randomly assigned to either the experimental group (those receiving program services) or the control group. A control group is used to assess the effect of program activities on participants who are receiving the services, products, or activities being evaluated. The same information is collected for people in the control group and those in the experimental group.
US Environmental Protection Agency. (2007). Program Evaluation Glossary. Office of the Administrator/Office of Policy/Office of Strategic Environmental Management/Evaluation Support Division.