The literature assessing whether mutual fund managers have skill typically regards skill as an immutable attribute of the manager or the fund. We show that many measures of skill, such as returns, alphas, and measures of stock-picking and market-timing, appear to vary over the business cycle. We...

The network model also explains why societies with a high prevalence of contagious disease might evolve toward growth-inhibiting social institutions and how small initial differences can produce large divergence in incomes. Empirical work uses differences in the prevalence of diseases spread by...