What is the purpose of using a control group in experiments?

The purpose of using a control group in experiments is to provide a baseline comparison. A control group allows researchers to observe the effects of the experimental treatment or variable against a standard condition where the treatment is absent or held constant. This comparison is crucial for determining whether any observed changes in the experimental group are genuinely due to the treatment being tested, rather than other factors or variables.

By isolating the effect of the experimental manipulation, the control group helps to establish a clearer cause-and-effect relationship. It enables researchers to understand the influence of the independent variable on the dependent variable, thus leading to more reliable and valid conclusions.

In contrast, manipulating experimental variables without a control group can lead to inconclusive results since there would be no reference point to determine the effect of those manipulations. Similarly, increasing sample diversity or implementing random assignment, while beneficial for improving the robustness of a study, do not address the need for a baseline against which the experimental effects can be measured.