What is the primary purpose of randomization in experiments?

• A. To reduce confounding by balancing known and unknown factors across groups.
• B. To guarantee causal conclusions.
• C. To increase data leakage.
• D. To shorten study duration.

Answer: (A)

Randomization is used to minimize confounding by balancing both known and unknown factors across experimental groups. By assigning participants to groups by chance, any differences in characteristics that could influence the outcome—whether we’ve measured them or not—tend to be spread evenly. This makes it more likely that observed differences in outcomes are due to the intervention itself rather than preexisting differences between groups, supporting a clearer interpretation of causal effects.

It doesn’t guarantee causal conclusions, because other issues like noncompliance, missing data, measurement error, or biases in study design can still affect results. Randomization won’t shorten study duration, nor does it purposefully increase data leakage.