The post-World War II period has seen substantial changes in the distribution of GDP per worker around the world. In the upper half of the distribution, a number of countries have exhibited large increases in income relative to the richest countries. In the bottom half, several countries have...

R&D-based growth theory suggests that a larger population size raises either the long-run rate of economic growth ("strong scale effect") or the level of per capita income ("weak scale effect"), with far-reaching policy implications. However, for modern times there is little empirical support...