"A randomized controlled trial (RCT) is a way of doing 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. In an RCT, the programme or policy is viewed as an ‘intervention’ in which a treatment – the elements of the programme/policy being evaluated – is tested for how well it achieves its objectives, as measured by a predetermined set of indicators. The strength of an RCT 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 [...] The distinguishing feature of an RCT is the random assignment of members of the population eligible for treatment to either one or more treatment groups (who receive the intervention treatment or variations of it) or to the control group (who receive either no intervention or the usual intervention, if the treatment is an innovation to an existing intervention). The effects on specific impact areas for the different groups are compared after set periods of time." (Page 1)