ABSTRACT
In double-blind clinical trials, randomization and blinding are often employed to prevent bias from clinical/statistical assessment of a test treatment under investigation. Randomization/blinding plays an important role in the conduct of clinical trials. Randomization/blinding not only generates comparable groups of patients who constitute representative samples from the intended (target) patient population but also enables valid statistical tests for clinical evaluation of the study drug. Randomization/blinding in clinical trials involves random recruitment of the patients from the targeted population and random assignment of patients to the treatments. For a valid statistical assessment of the efŒcacy and safety of a study drug, it is important that a representative sample of qualiŒed patients be randomly selected from the target patient population. Randomization avoids subjective selection bias for the integrity and scientiŒc and/or statistical validity of the intended clinical trials. Patients participating in the clinical trials are randomly assigned to one of the treatments under study, which avoids subjective assignment of treatments. On the other hand, blinding is the guard for preventing subjective evaluation bias and consequently ensures scientiŒc and/or statistical validity of the intended clinical trials. When there is heterogeneity in demographics and/or patient characteristics, randomization with blocking and/or stratiŒcation is helpful in removing the potential bias that might occur due to the differences in demographics and/or patient characteristics. Under randomization and blinding, statistical inference can be drawn under some probability distribution assumption of the intended patient population. The probability distribution assumption depends on the method of randomization under a randomization (population) model. A study without randomization/blinding will result in the violation of the probability distribution assumption and consequently no accurate and reliable statistical inference on the study drug can be drawn.
