Non-equivalent control groups are used in research studies to compare the effects of an intervention or treatment. Unlike traditional control groups, which are randomly assigned, non-equivalent control groups consist of participants who are not randomly selected. This means that the groups may differ in important ways, making it harder to determine if the observed effects are due to the treatment or other factors. Researchers often use non-equivalent control groups when random assignment is not feasible, such as in educational settings or community programs. By comparing outcomes between the treatment group and the non-equivalent control group, researchers can still gain insights, although they must be cautious about drawing definitive conclusions due to potential biases.