From local to global: extrapolating experiments

The use of randomised control trials (RCTs) in evaluating the design and efficacy of policies has exploded in the last decade. New papers appear every week. But while RCTs are quickly becoming the gold standard for impact evaluations in international development and aid interventions, questions persist about what the results of an RCT in one context can tell us about the probable results of similar programme implemented in another context. Indeed, such questions are not unique to RCT’s but apply to the full set of empirical tools that economists apply in estimating policy impacts and outcomes.