A key tenet of the theory of human capital is that investment in skills results in higher productivity. The previous literature has estimated the degree of investment in human capital for individuals by looking at individual wage growth as a proxy for productivity growth. In this paper, we have...

Wages have been spreading out across workers over time - or in other words, the 90th/50th wage ratio has risen over time. A key question is, has the productivity distribution also spread out across worker skill levels over time? Using our calculations of productivity by skill level for the U.S.,...