There is good research on policy, but because so many individual policies are in play at any given moment, it is very difficult for policy researchers or policy makers to figure out the effects of anything.
Discussions about when generalization is most likely to take place are healthy and welcome. But they are not academic. America's schools are not getting better fast enough, and achievement gaps by race and class remain unacceptable.
Valentine's Day is this Sunday. If you are spending it thinking about effect sizes or research designs or education policy, shame on you. Unless, of course, that sort of thing turns you on.
My wife Nancy and I were recently in Barcelona, a beautiful and fascinating city famous for its innovations in architecture, art, and design. We were speaking to various groups about evidence-based reform in education and about cooperative learning.