Intelligence, Human Capital, and Economic Growth: An Extreme Bounds Analysis

Human capital plays an important role in the theory of economic growth, but it has been difficult to measure this abstract concept. We survey the psychological literature on cross-cultural IQ tests, and conclude that modern intelligence tests are well-suited for measuring an important form of a nation’s human capital. Using a new database compiled by Lynn and Vanhanen (2002), we show that national average IQ has a robust positive relationship with economic growth. Using a methodology derived from Sala-i-Martin (1997a), we show that in growth regressions that include only robust control variables, IQ is statistically significant in 99.7% of these 1330 regressions. A strong relationship persists even when OECD countries are excluded from the sample. Conditional on GDP per capita in 1960 and other control variables, a 1 point increase in a nation’s average IQ is associated with a persistent 0.13% annual increase in GDP per capita