The term CONTROL IN A CLINICAL STUDY can be summarized as the use of a PLACEBO in a clinical study. A PLACEBO is an inactive substance or treatment that is used as a control in a clinical study, to compare the effects of the active treatment being tested. The PLACEBO is given to the control group, while the experimental group receives the active treatment. This allows researchers to measure the effectiveness of the active treatment by comparing the results of the two groups.