What is the purpose of randomization in clinical trials?

Randomization in clinical trials serves as a fundamental mechanism to ensure that the treatment groups are comparable. By randomly assigning participants to different groups, researchers create an equal chance for all participants to belong to any group, which helps to eliminate systematic biases that could affect the results. This process minimizes the impact of confounding variables—factors that can influence both the treatment effect and the outcome—thus strengthening the validity of the causal inferences made from the trial.

When groups are comparable, any differences observed in outcomes can more confidently be attributed to the intervention being tested rather than to pre-existing differences between the groups. This helps in securing the internal validity of the study. Consequently, the reliability of the results is enhanced, making findings more generalizable to the broader population, assuming that the sample is representative.

The mechanism of randomization does not aim to attract more participants, simplify data collection, or guarantee positive outcomes. Rather, it is a rigorous methodological approach vital for the integrity and trustworthiness of clinical research.