Or is at least correlated. And that correlation is quite brittle - if you do things like split the world into developed and undeveloped, the correlations seem t

Or is at least correlated. And that correlation is quite brittle - if you do things like split the world into developed and undeveloped, the correlations seem to vanish (suggesting Simpson's paradox). http://www.manhattan-institute.org/pdf/e21_01.pdf http://www.manhattan-institute.org/pdf/e21_01.pdf The stats supporting this are not very solid.