Basics Wait List Control Groups in Psychology Experiments By Nancy Schimelpfening Nancy Schimelpfening Nancy Schimelpfening, MS is the administrator for the non-profit depression support group Depression Sanctuary. Nancy has a lifetime of experience with depression, experiencing firsthand how devastating this illness can be. Learn about our editorial process Updated on June 20, 2021 Fact checked Verywell Mind content is rigorously reviewed by a team of qualified and experienced fact checkers. Fact checkers review articles for factual accuracy, relevance, and timeliness. We rely on the most current and reputable sources, which are cited in the text and listed at the bottom of each article. Content is fact checked after it has been edited and before publication. Learn more. by Cara Lustik Fact checked by Cara Lustik LinkedIn Cara Lustik is a fact-checker and copywriter. Learn about our editorial process Print Benjamin Rondel/Cultura/Getty Images In psychotherapy research, a wait list control group is a group of participants who do not receive the experimental treatment, but who are put on a waiting list to receive the intervention after the active treatment group does. The wait list control group serves two purposes. First, it provides an untreated comparison for the active experimental group to determine if the treatment had an effect. By serving as a comparison group, researchers are able to isolate the independent variable and look at the impact it had. Second, it allows the wait-listed participants an opportunity to obtain the intervention at a later date. In an experiment, people are randomly selected to be in the wait list group. They also closely resemble the participants who are in the experimental group (or the individuals who receive the treatment). Importance 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 treatment. The wait list control group serves as a benchmark, allowing researchers to compare the experimental group to the wait list control group to see what sort of impact changes to the independent variable produced. It essentially allows researchers to assess the effect of the intervention against not receiving treatment during that same time period (while still providing all participants with treatment eventually). Because participants have been randomly assigned to either the wait list control group or the experimental group, it can be assumed that the groups are comparable. Any differences between the two groups are therefore the result of the manipulations of the independent variable. The experimenters carry out the exact same procedures with both groups with the exception of the manipulation of the independent variable in the experimental group. Types of Research Many types of psychological and behavioral health research use wait list control groups. It is used in studying the effect of interventions on alcohol consumption, depression and anxiety, and promoting healthy behaviors, such as stress management. Shortcomings While using wait list control groups has been seen as an ethical alternative to having a control group, it can pose problems. A 2013 study in BMC Medical Research Methodology suggested that using a wait list control group may artificially inflate estimates of the intervention effect. The idea is that by telling people to wait for treatment, they are stalled in the stage of change related to readiness and do not move forward to action on their own. So rather than attempting behavior change on their own, or seeking other avenues of help, they wait, possibly showing less improvement than a simple control group would show. In this particular study, researchers looked at the effect of an intervention on problem drinking. 4 Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. American Psychological Association Dictionary of Psychology. APA Dictionary of Psychology: wait-list control group. Kinser PA, Robins JL. Control group design: Enhancing rigor in research of mind-body therapies for depression. Evidence-Based Complementary and Alternative Medicine. 2013;2013:1-10. doi:10.1155/2013/140467 McCauley JL, Killeen T, Gros DF, Brady KT, Back SE. Posttraumatic stress disorder and co-occurring substance use disorders: Advances in assessment and treatment. Clin Psychol (New York). 2012;19(3). doi:10.1111/cpsp.1200 Cunningham JA, Kypri K, McCambridge J. Exploratory randomized controlled trial evaluating the impact of a waiting list control design. BMC Med Res Methodol. 2013;13(1):150. doi:10.1186/1471-2288-13-150 By Nancy Schimelpfening Nancy Schimelpfening, MS is the administrator for the non-profit depression support group Depression Sanctuary. Nancy has a lifetime of experience with depression, experiencing firsthand how devastating this illness can be. See Our Editorial Process Meet Our Review Board Share Feedback Was this page helpful? Thanks for your feedback! What is your feedback? Other Helpful Report an Error Submit Speak to a Therapist Online Advertiser Disclosure × The offers that appear in this table are from partnerships from which Verywell Mind receives compensation.