First, IQ pays. Holding education constant, an extra point of IQ raises earnings by about 1%.6 Second, holding IQ constant, the education premium shrinks but never vanishes. In 1999, 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
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