This article is part of the network’s archive of useful research information. This article is closed to new comments due to inactivity. We welcome new content which can be done by submitting an article for review or take part in discussions in an open topic or submit a blog post to take your discussions online.
Randomised controlled trials (RCTs) are widely accepted as the preferred study design for evaluating healthcare interventions. When the sample size is determined, a (target) difference is typically specified that the RCT is designed to detect. This provides reassurance that the study will be informative, i.e., should such a difference exist, it is likely to be detected with the required statistical precision. The aim of this review was to identify potential methods for specifying the target difference in an RCT sample size calculation.