>The Finnish schools are equal in the sense that socio-economic background has a smaller effect on study outcomes than elsewhere Wouldn't Finland's flatter inc

>The Finnish schools are equal in the sense that socio-economic background has a smaller effect on study outcomes than elsewhere Wouldn't Finland's flatter income distribution be a potential confounding variable in this case? When the difference between the 25th and 75th percentile in income means less in absolute terms, there are probably a whole lot of things that are associated with income in the US that show less of an association in Finland. For example, high-IQ types might be less likely to strive for high-income occupations in Finland than in the US, lessening the correlation between income and IQ. With child IQ being strongly correlated to parental IQ, it's easy to see how this could lessen the correlation between school performance and economic background. Of course, you may have been comparing Finland to other countries with similarly flat income distributions, which would make my above point moot. Even then though, it's not clear that Finland's education system is necessarily "more equal" than other countries -- it could just be more effective. If the school system in, say, Norway is less effective than in Finland, higher-income students are likely to see less of a drop in scores because they have more educational resources outside of the system.