In a quantitative study, a control group is a group of individuals who have not been exposed to the element whose effects are being tested. It is used as a reference for analysis. In the case of an advertising post-test, for example, the control group will correspond to individuals who have not been exposed to the advertising campaign. It is to the results of this control group that it will be interesting to compare those of people exposed to ads in order to measure the impact of the campaign.
