What is a key advantage of random assignment in experiments?

A key advantage of random assignment in experiments is that it ensures an equal distribution of participants across different groups. This process reduces the potential for biases that could affect the outcome of the study. By randomly assigning participants, researchers can control for both known and unknown variables that might influence the results, making it more likely that any differences observed between the groups can be attributed to the treatment or intervention rather than pre-existing differences among the participants.

Random assignment contributes to the internal validity of an experiment, as it helps to create equivalent groups in terms of demographics and characteristics. This is critical for establishing causal relationships, as it minimizes the risk of confounding factors impacting the findings. In well-designed experiments, the use of random assignment enhances the credibility of the results, allowing researchers to make more accurate inferences about the effectiveness of the intervention being tested.

The other options lack this fundamental advantage. For instance, the need for a control group remains essential for comparison, and random assignment does not inherently guarantee larger sample sizes or increase variability among groups.