Social & Preventive Medicine In a controlled trail to compare two treatments, the main purpose of randomization is to ensure that : A The two groups will be similar in prognostic factors. B The clinician does not know which treatment the subj ects will receive. C The sample may be referred to a known population. D The clinician can predict in advance which treatment the subjects will receive. 💡 Explanation In a controlled trail to compare two treatments, the main purpose of randomization is to ensure that : ✓ Correct Answer: A. The two groups will be similar in prognostic factors.