The major purpose of randomization in a clinical trial is to:

Clinical trials are mostly concerned with evaluating therapeutic agents, mainly drugs. Randomization is an attempt to eliminate bias and allow for comparability. In a randomized controlled trial – the purpose of randomization is to reduce selection bias in allocation to treatment so as to balance the treatment groups with respect to known and unknown prognostic variable. However, baseline characteristics of intervention and control groups should be similar. Investigator’s bias is minimized by double-blinding. The sample size required is independent of the hypothesis. The drop-outs from the trial should be excluded from the analysis.