A review of the measures of the stock of human capital used in empirical growth research reveals that human capital is mostly poorly proxied. The simple use of the most common proxy, average years of schooling of the working-age population, misspecifies the relationship between education and the...

We employ a combination of school fixed effects and IV estimation to estimate the effect of class size on student performance in 18 countries. Using the random part of the class-size variation between two adjacent grades within individual schools allows us to identify causal class-size effects....