Ethics in cluster randomised trials: a grey zone.

ABSTRACT

Cluster randomised trials (CRTs) are controlled trials in which the randomisation is applied to groups of individuals (clusters) as opposed to individual research participants. CRTs are increasingly being used in a wide variety of research with public health implications (including education). Well conducted CRTs can have a significant effect on policy-making. However, CRTs are only justified in specific circumstances where they might be considered suitable this might be for reasons of scientific validity, feasibility, appropriateness, to reduce chances of contamination, etc.