Sample size in cluster randomised trials with unequal clusters
نویسندگان
چکیده
Objectives The aim of RCTs is to obtain unbiased estimates of treatment effects to answer the question of interest. In a cluster randomised trial (CRT), maximum statistical efficiency is obtained if an equal sized sample from each cluster is selected. In practice, the ability to achieve equal cluster size is an exception rather than the norm. Two CRTs run by the Leeds CTRU; TRACS (Training Caregivers After Stroke) and LoTS Care (Longer Term Stroke Care) are used to demonstrate how this issue can be dealt with practically.
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