The control group in an experiment is the group who does not receive any treatment and is used as a benchmark against which other test results are measured. This group includes individuals who are very similar in many ways to the individuals who are receiving the treatment, in terms of age, gender, race or other factors.
A control group is used in an experiment as a point of comparison, so that it can be isolated in testing that the experiment did, or did not, affect the patients in the ways that were intended. Members of the control group often are given placebos and do not know that they are part of the control group so that the researcher can determine the effectiveness of what is being studied.
Testing Using Control Groups
- In an experiment in which blood pressure medication is tested, one group is given the blood pressure medication while the control group is given a placebo pill.
- In a test of anxiety treatment, one group attends individual therapy sessions and receives a new medication. The control group receives only an inert pill.
- A treatment for drug addiction is being tested. A group of meth addicts are given the treatment while the control group is given the placebo.
- Researchers are testing the effectiveness of a drug intended to reduce symptoms of Crohn's disease. Many sufferers of Crohn's disease are recruited for the effort and the group that receives the placebo is the control group.
- A treatment for hair loss in men is being tested. Men of the same age range are gathered. One group receives an application with the active ingredient while the control group receives an application that appears the same but does not have the active ingredient in it.
- Researchers are testing an anti-wrinkle facial product. They recruit volunteers all within the age range of 38-45 and distribute bottles to everyone that appear to hold the same product. However, the control group receives bottles that do not have the compound that is intended to reduce wrinkles.
- Doctors are studying a weight loss drug. Volunteers for the study are recruited. All volunteers are in their thirties and are at least 50 pounds overweight. The control group receives a pill pack that looks exactly the same as the packet that the others received, but the control group's pack is a placebo.
- Psychiatrists are testing the effectiveness of a proposed ADHD drug. They recruit parents who are willing to allow their child to be a part of the clinical tests. All of the children are between the ages of 9 and 14 and have been diagnosed with ADHD. The psychiatrists involve the parents and the teachers in questionnaires throughout the process but only one group has the pill that is being tested while the other group of children has a sugar pill.
- Tests are being run to determine whether a newly developed medication can help to ease the effects of Post Traumatic Stress Disorder. Researchers recruit male volunteers aged 30 - 45 and distribute the medication. The control group receives what appears to be the same, but is only an inert pill.
Now you see how control groups are used in experiments.