Earnings Inequality among Males in the United States: Trends and the Effect of Labor Force Growth
利用1968-79年数据，分析美国男性劳动力群体内收入不平等的变化，发现劳动力增长率通过影响人力资本投资回报，加剧了生命周期早期的收入不平等。
We analyze the variance of log earnings within labor force cohorts of U.S. males with particular attention to the influence of labor force growth rates. Estimates with data from the 1968-79 current population surveys reveal increases in earnings inequality within labor force cohorts even after we control for the level of education, experience, and unemployment. A model of human capital investment is used to analyze differences among cohorts in the life-cycle profile of the variance of log earnings. It is shown that a pattern of sharply increasing and then declining labor force growth rates will tend to raise the return on human capital investment and thereby increase the variance of postschooling investment and log earnings early in the life cycle. This positive effect on relative earnings inequality should decline with experience and possibly become negative. Because of the post-World War II baby boom and baby bust, recent labor force entrants have faced just such a pattern of actual and projected labor force growth rates during their work life. An extended model is tested and generally confirmed using estimates and forecasts of labor force growth rates for the period 1920-2000.