Randomized Controlled Trials (RCTs): Methodological Briefs – Impact Evaluation No. 7

A randomized controlled trial (RCT) is an experimental form of impact evaluation in which the population receiving the programme or policy intervention is chosen at random from the eligible population, and a control group is also chosen at random from the same eligible population. It tests the extent to which specific, planned impacts are being achieved. The distinguishing feature of an RCT is the random assignment of units (e.g. people, schools, villages, etc.) to the intervention or control groups. One of its strengths is that it provides a very powerful response to questions of causality, helping evaluators and programme implementers to know that what is being achieved is as a result of the intervention and not anything else.