a comprehensive review of earlier studies found that correcting for IQ reduces the education premium by an average of 18%.7 When researchers correct for scores on the Armed Forces Qualification Test (AFQT), an especially high-quality IQ test, the education premium typically declines by 20–30%.8 Correcting for mathematical ability may tilt the scales even more; the most prominent researchers to do so report a 40–50% decline in the education premium for men and a 30–40% decline for women.9 Internationally, correcting for cognitive skill cuts the payoff for years of education by 20%, leaving
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