Random assignment is a method used in experiments to ensure that participants are placed into different groups in a way that is completely random. This process helps to eliminate bias, making sure that each group is similar in characteristics, such as age or gender, at the start of the study. By doing this, researchers can be more confident that any differences observed between the groups are due to the treatment or intervention being tested. This technique is crucial in fields like psychology and medicine, where it helps to establish cause-and-effect relationships. When participants are randomly assigned, it increases the validity of the results, allowing researchers to draw more accurate conclusions about the effectiveness of a particular treatment or intervention.