What is the primary purpose of randomization in a randomized controlled trial?
- A To ensure that the sample size is adequate for detecting a difference
- B To eliminate all measurement errors in outcome assessment
- C To distribute known and unknown confounding factors equally between groups ✓
- D To guarantee that every participant receives an effective treatment
Correct answer: C. To distribute known and unknown confounding factors equally between groups
Explanation
Randomization allocates participants to groups by chance so that both known and unknown confounders are expected to be balanced across arms. Sample size adequacy is achieved through power calculation, blinding addresses measurement bias, and randomization says nothing about treatment effectiveness. This balancing of unknown confounders is exactly what matching and stratification cannot achieve, which is why randomization remains the hallmark of experimental designs.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
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