We estimate the relative roles of factor inputs and productivity in explaining the level of economic development, which is measured as output per worker. For a large sample of countries, we show that alternative identifying productivity assumptions and alternative measures of human capital have...

We estimate the effect of class size on student performance in 18 countries, combining school fixed effects and instrumental variables to identify random class-size variation between two adjacent grades within individual schools. Conventional estimates of class-size effects are shown to be...