Definition: In a study dealing with a therapy outcome, a wait list control group is a group that is assigned to a waiting list to receive an intervention after the active treatment group does. A wait list control group serves the purpose of providing an untreated comparison for the active treatment group, while at the same time allowing the wait-listed participants an opportunity to obtain the intervention at a later date.
A wait list control group is often thought to be preferable to a no-treatment control group in cases where it would be unethical to deny participants access to a treatment.
