In a controlled trial to compare two treatments, the main purpose of randomization is to ensure that-
Randomization is an effo to control bias and allow for compatibility. Theoretically, it is possible to assure compatibility by matching. But when one matches one can only match those factors which are known to be impoant. There may be other factors which are known to be impoant. (refer pgno:82 park 23 rd edition)
The two groups will be similar in prognostic factors
The clinician does not know which treatment the subjects will receive
The sample may be referred to a known population
The clinician can predict in advance which treatment the subjects will receive
Epidemiology