What is the purpose of using random assignment in experiments?

Random assignment plays a crucial role in experimental research by minimizing bias and ensuring that the groups being compared are equivalent at the start of the experiment. When researchers randomly assign participants to different groups, it helps to distribute known and unknown variables evenly across those groups. This randomization reduces the likelihood that differences observed in the outcomes between groups can be attributed to pre-existing differences among participants, rather than the treatment or intervention being tested.

By creating equivalent groups, researchers can more confidently attribute any observed changes in the dependent variable to the manipulation of the independent variable. This is essential for establishing causal relationships and enhancing the internal validity of the experiment. Ensuring that participant characteristics do not systematically differ across groups strengthens the credibility of the findings, making it easier to draw reliable conclusions from the study.