Human Capital and Wage Inequality: Analysis of Recent Changes

与过去形成鲜明对比的是，近20年来，美国经济的平均实际工资增长一直停滞不前。这种停滞不前的增长掩盖了高收入者和低收入者之间实际工资趋势上同样前所未有的差异，这种差异在20世纪80年代变得明显。较熟练和受教育程度较高的工人的实际工资继续显著增长，而受教育程度和技能较低的工人的工资保持不变，甚至有所下降。因此，在近20年的时间里，平均生活水平几乎没有提高，工资和收入不平等却在加剧。从劳动力市场的角度来看这种情况，有两个基本假设可以解释这种不断扩大的收入不平等。其一，信息和新技术的增长以及经济活动的全球化导致对受过良好教育和灵活的劳动力的需求增加。另一种是，期望的劳动力素质与实际供给之间的差距越来越大，工人的工作质量实际上可能已经恶化。本研究的目的是利用当前人口调查的微观数据分析1967年至1990年的收入不平等，以阐明哪些假设或组合解释了收入不平等的增加。通过人力资本分析，研究男性工资不平等的年度变化。该分析中详尽且可计算的因素是：(1)人力资本水平的变化和员工之间的分散；(2)人力资本投资回报率的变化；(3)收益率离散度的变化。该分析还区分了学校教育和就业市场投资的影响，以及年度不平等和终身不平等的影响。要更全面地了解收入不平等的发展和前景，就需要分析供给对工资结构和就业市场投资成本变化的反应。还将尝试直接或间接地确定可能影响收入不平等未来进程的供应调整的障碍。

In sharp contrast to the past, the American economy has experienced stagnation in the growth of average, real wages over almost two decades now. This stagnant growth covers an equally unprecedented divergence in the trend of real wages between high and low wage earners, which became apparent in the 1980's. The more skilled and educated workers continued to experience significant growth in real wages, while wages of the less educated and skilled remained the same or even declined. Consequently, as the average standard of living has barely increased in almost two decades, wage and income inequality has risen. Looking at this situation form the vantage point of the labor market, two basic hypotheses emerge to explain this growing income inequality. One is that the growth of information and new technologies and the globalization of economic activity has led to increased demand for a well educated and flexible work force. The other is that there is a growing gap between desired labor force quality and its actual supply, and that the quality of worker performance may have actually deteriorated. The purpose of this research is to analyze earnings inequality from 1967 through 1990 using micro data from the Current Population Survey in order to shed light on which hypotheses or combination explains the increase in earnings inequality. Annual changes in wage inequality of men will be studied by means of human capital analysis. The exhaustive and computable factors in this analysis are: (1) changes in levels and dispersion of human capital across workers; (2) changes in rates of returns on human capital investments; and (3) changes in dispersion of rates of return. The analysis also distinguishes between effects of schooling and of job market investments, as well as between annual and life-time inequality. A more complete understanding of the developments of and prospects for earnings inequality requires the analyses of supply responses to changes in the wage structure and in job market investment costs. An attempt will also be made to identify, directly or indirectly, obstacles to supply adjustments which may affect the future course of earnings inequality.