This blog post and its associated replies, written by Jed Friedman for the World Bank, describes a process of using analytic methods to overcome some of the assumptions that must be made when extrapolating results from evaluations to other settings. The blog post includes a number of detailed replies which further enhance the ideas initially presented.
"Imagine you are a local policy maker who just read about a new effective social program in another city and you want to determine whether this program would work for your area. This question, of course, concerns the external validity of program impacts, which we have discussed repeatedly here on this blog (see here and here for recent examples). The act of extrapolating evaluation results to other settings must always be driven, in part, by key assumptions – it’s unavoidable. But there are analytic methods that sometimes assist this extrapolation, thereby reducing the severity of the necessary assumptions." (Friedman, 2014)
Friedman, J., (2014), Will that successful intervention over there get results over here? We can never answer with full certainty, but a few steps may help. Retrieved from: http://blogs.worldbank.org/impactevaluations/will-successful-interventio...