I really like your argument (probably because you make a point that is important to me), but I think we also have to accept the realities of methodology. The va

I really like your argument (probably because you make a point that is important to me), but I think we also have to accept the realities of methodology. The variables which you (and I) would like to measure are much harder to get at. They require more time, good definitions of hard to define things, and more resources. I think the multitude of different ways to measure the happiness and well-being of a person are a good reminder of this. So researchers go for something that is easy to measure in a shorter time frame and which still provides some indication (some studies show correlation between college education and happiness, college education and income). Of course you would like to measure those things directly instead of using a proxy, but for the short term this can be good enough. You make some interesting connections between different opportunities for girls and boys in South Korea and single-sex schools, but I would be careful to correlate the two. It could very well be that coeducation is helpful in achieving equality on a society level, but maybe after equality has been achieved single-sex education might prove more effective.