Recent research on the design of social experiments has highlighted the effects of different design choices on research findings. Since experiments rarely collect their samples using random selection, in order to address these external validity problems and design choices, recent research has focused on two areas. The first area is on methods for…

One purpose of educational research is to provide information about the likely impact of interventions or treatments on policy-relevant populations of students. Randomized experiments are useful for estimating the causal effects of interventions on the students in schools that participate in the experiments. Unfortunately, the samples of schools…