What is the purpose of a control group in an experiment?

The purpose of a control group in an experiment is to provide a baseline for comparison. This allows researchers to evaluate the effect of the independent variable by comparing the results obtained from the experimental group, which receives the treatment or intervention, to those from the control group, which does not. The control group acts as a standard that reflects what happens in the absence of the independent variable, thereby helping to isolate the effects of the variable being tested.

In this context, it becomes clear that the control group's outcomes serve as a critical reference point. If the experimental group shows a significant effect or change, researchers can attribute this to the manipulation of the independent variable, while any differences relative to the control group highlight the impact of that variable. This systematic approach is fundamental to scientific experimentation, ensuring that any observed effects are due to the treatment rather than other external factors.