5.3. The σ Convergence

The σconvergence refers to the dispersion of income across regions. In Barro and Sala-i-Martin (1995), the σ convergence is measured with the unweighted cross-sectional standard deviations of state per capita income. In addition to the standard-deviation, we consider here the coefficient of variation for a closer look at the data. The purpose of this section is to compare the dispersion of average incomes to the dispersion of top incomes.