I believe RCT is one of several ways of measuring impact of an intervention. Often, we try to answer the question; what has out intervention changed? With RCT, how can the following be addressed. 1. How do you control for other changes that occur simultaneousily with your intervention. Say, beside the milk, if the government intriduces a new sylabus. 2. What is the scope, in terms of time, in a RCT?