A group of subjects which receives a placebo instead of the experimental treatment but is treated in all other respects in the same way as the experimental group.
The group of people in an experimental study whose conditions remain constant; who are not exposed to the stimulus being studied.
A group of people who are not being treated but whose test data are used as a comparison in a study.
A cohort of participants that function as a benchmark for evaluating the effectiveness of an experimental treatment under assessment.