Randomization is done to reduce-

.randomization is a statisticaal procedure in which the paicipants are allocated to groups usually called study and control gropus.randomization is an approach to ensure comparability by the elimination of bias.randomisaton is the hea of a control trial.it ensures that the investigator has no control over the allocation of paicipants to groups.thus eliminating what is known as "SELECTION BIAS". ref:park&;s textbook,22 nd ed,pg 70