Inequality in the distribution of personal income in the world: How it is changing and why

The variance in the logarithms of per capita GDP in purchasing-power-parity prices increased in the world from 1960 to 1968 and decreased since the mid 1970s. In the later period the convergence in intercountry incomes more than offset any increase in within country inequality. Approximately two-thirds of this measure of world inequality is intercountry, three-tenths interhousehold within country inequality, and one-twentieth between gender differences in education. If China is excluded from the world sample, the decline in world inequality after 1975 is not evident. Measuring confidently trends in household and gender inequality will require much improved data.