Practical tips for surgical research. Ensuring balanced groups in surgical trials.

H igh-quality randomized controlled trials (RCTs) are the highest level of evidence in assessing the effectiveness of a treatment. It is random allocation that places RCTs in the highest level of evidence. The purpose of randomization is to create groups of patients that are comparable for known and unknown factors at the start of the trial so that any differences at the completion of the trial can be attributed to the treatment under investigation. The purpose of this article is to discuss the processes that would help create balanced groups and maintain between-group comparability through out the study period.