Problem
Usually, children in private K-12 schools obtain better test scores than those in public schools. This Might be because private schools are better at teaching the material, or there might be some other Explanation. Suppose that a charitable foundation is giving vouchers to parents who want to transfer their children from public to private schools. More parents apply for these vouchers than the foundation can provide. If you are a social scientist solely interested in the question of whether private schools have some kind of positive effect on test scores, how would you advise the foundation to award the vouchers? Justify your advice.