Improving the efficiency of evidence-based interventions: The strengths and limitations of randomised controlled trials

Globally, randomised controlled trials (RCTs) are increasingly seen as the gold standard of programme evaluation, representing the best way to determine whether new interventions are effective – but they are not without limitations. In this article, we discuss the phases of scientific discovery and the research standards that are necessary before scaling up interventions. We also outline the core characteristics of RCTs, such as randomisation, efficacy and effectiveness, and discuss the benefits of using the RCT as the standard of intervention evaluation. We discuss how ‘realist’ evaluation contributes to what policymakers need to know in order to make a decision about an evaluation and alternatives to the RCT, such as stepped wedge, regression discontinuity, non-randomised cohort, and time series designs