What role does randomization play in an experiment?

Randomization is a critical component of experimental design because it helps to eliminate bias in the assignment of treatments to subjects. By randomly assigning participants to treatment groups, researchers can ensure that each group is similar in all respects except for the treatment they receive. This process mitigates the influence of confounding variables that could affect the outcome, allowing for a more accurate assessment of the treatment's effect.

When subjects are assigned to groups randomly, it improves the internal validity of the experiment. That is, it strengthens the inference that any observed differences in outcomes between the groups are due to the treatment itself and not some other factor. This helps establish a causal relationship between the treatment and the response variable.

Other options describe aspects that don’t capture the main purpose of randomization. For example, managing the budget is unrelated to how treatments are assigned, and ensuring that everyone receives the same treatment does not align with the purpose of randomization, which is to diversify treatment experiences. While larger sample sizes can improve the robustness of results, randomization is not directly related to sample size but rather to how subjects are chosen for different treatment groups.