Measuring Trends in Income Variability

Using PSID data from 1968 to 2005, we find that the volatility of family income has increased over time (a trend that is robust to a large variety of modeling choices) but the trend in individual income volatility is less clear. Measurement error cannot fully account for these facts, but the increasing covariance of individual incomes within the family (driven by increases in the correlation of head and spouse earnings, due largely to the increased proportion of families with two earners) can.