The Course of Income Inequality as a Cohort Ages into Old-Age

Several researchers have shown that income inequality of a cohort increases as the cohort ages. The various studies examining cohort income inequality use a variety of data, measures, and methods. Is the U.S. experience documented in other studies due (1) to cumulative advantages and disadvantages continuing to work through market income into retirement, (2) to the relative weakness of the U.S. Social Security program, or (3) to potential biases due to data, measures and/or methods? This study examines cohort income inequality using nationally representative longitudinal data and a variety of inequality measures to follow a large sample of individuals from their late pre-retirement years into their retirement years. The findings are: (1) the course of the Gini coefficient is flat as the cohort ages into retirement, (2) but the course of income inequality as this cohort ages into retirement depends on the inequality measure employed, and (3) the trend results suggest that what is going on in the bottom part of the distribution is different from what is going on in the upper part.