The aim of this review is to determine whetherrandomised controlled trials (RCTs) lead to the same effect size and variance as non-randomised studies (NRSs) of similar policy interventions; and whether these findings can be explained by other factors associated with the interventions or their evaluation.This systematic review was published by EPPI-Centre in 2011.Systematic reviews aim to find as much as possible of the research relevant to the particular research questions, and use explicit methods to identify what can reliably be said on the basis of these studies.
