ABSTRACT
This chapter considers the questions of what counts as evidence in evaluation, and explores three approaches that attempt to provide a method for the synthesis of research, with each either attempting to provide an underpinning for the way in which either interventions can be evaluated. It also considers the strengths and weaknesses of each, as well as the assumptions they hold about what counts as good research. Many researchers regard the randomised controlled trial (RCT) and systematic review as representing a gold standard for the creation, assessment and evaluation of evidence. The RCT approach carries with it a range of ontological and epistemological assumptions that need to be considered carefully to assess whether they can be translated into social research. In countries such as the United States or Australia, different states may adopt different approaches to policy, making comparison between those interventions possible, and so some policy writers suggest they form 'natural experiments'.
