This paper's aim is to explore the uses and limitations of randomised controlled trials (RCTs) for evaluating complex interventions, with a particular focus on sample recruitment and retention issues.
This is an invited critique of a previous paper.
RCTs have many limitations. It is particularly important to consider issues relating to the sample they recruit and retain. Nonetheless, they remain a uniquely powerful way to exclude other potential explanations for outcomes and therefore provide robust evidence for the effectiveness of specific interventions.
It is hoped that vigorous debate may contribute to a deepened understanding of the nature, limitations and potential contribution of RCTs to understanding the impact of different ways of helping people.
