Trends in U. S. Wage Inequality: Re-Assessing the Revisionists

A large literature documents a substantial rise in U. S. wage inequality and educational wage differentials over the past several decades and finds that these trends can be primarily accounted for by shifts in the supply of and demand for skills reinforced by the erosion of labor market institutions affecting the wages of low- and middle-wage workers. Drawing on an additional decade of data, a number of recent contributions reject this consensus to conclude that (1) the rise in wage inequality was an “episodic” event of the first-half of the 1980s rather than a "secular” phenomenon, (2) this rise was largely caused by a falling minimum wage rather than by supply and demand factors; and (3) rising residual wage inequality since the mid-1980s is explained by confounding effects of labor force composition rather than true increases in inequality within detailed demographic groups. We reexamine these claims using detailed data from the Current Population Survey and find only limited support. Although the growth of overall inequality in the U. S. slowed in the 1990s, upper tail inequality rose almost as rapidly during the 1990s as during the 1980s. A decomposition applied to the CPS data reveals large and persistent rise in within-group earnings inequality over the past several decades, controlling for changes in labor force composition. While changes in the minimum wage can potentially account for much of the movement in lower tail earnings inequality, strong time series correlations of the evolution of the real minimum wage and upper tail wage inequality raise questions concerning the causal interpretation of such relationships. We also find that changes in the college/high school wage premium appear to be well captured by standard models emphasizing rapid secular growth in the relative demand for skills and fluctuations in the rate of growth of the relative supply of college workers – though these models do not accurately predict the slowdown in the growth of the college/high-school gap during the 1990s. We conclude that these patterns are not adequately explained by either a ‘unicausal’ skill-biased technical change explanation or a revisionist hypothesis focused primarily on minimum wages and mechanical labor force compositional effects. We speculate that these puzzles can be partially reconciled by a modified version of the skill-biased technical change hypothesis that generates a polarization of skill demands.

Trends in U.S. Wage Inequality: Re-Assessing the Revisionists

A recent "revisionist " literature characterizes the pronounced rise in U.S. wage inequality since 1980 as an "episodic " event of the first-half of the 1980s driven by non-market factors (particularly a falling real minimum wage) and concludes that continued increases in wage inequality since the late 1980s substantially reflect the mechanical confounding effects of changes in labor force composition. Analyzing data from the Current Population Survey for 1963 to 2005, we find limited support for these claims. The slowing of the growth of overall wage inequality in the 1990s hides a divergence in the paths of upper-tail (90/50) inequality -- which has increased steadily since 1980, even adjusting for changes in labor force composition -- and lower tail (50/10) inequality, which rose sharply in the first-half of the 1980s and plateaued or contracted thereafter. Fluctuations in the real minimum wage are not a plausible explanation for these trends since the bulk of inequality growth occurs above the median of the wage distribution. Models emphasizing rapid secular growth in the relative demand for skills -- attributable to skill-biased technical change -- and a sharp deceleration in the relative supply of college workers in the 1980s do an excellent job of capturing the evolution of the college/high-school wage premium over four decades. But these models also imply a puzzling deceleration in relative demand growth for college workers in the early 1990s, also visible in a recent "polarization" of skill demands in which employment has expanded in high-wage and low-wage work at the expense of middle-wage jobs. These patterns are potentially reconciled by a modified version of the skill-biased technical change hypothesis that emphasizes the role of information technology in complementing abstract (high-education) tasks and substituting for routine (middle-education) tasks.

Rising Wage Inequality: The Role of Composition and Prices

During the early 1980s, earnings inequality in the U.S. labor market rose relatively uniformly throughout the wage distribution. But this uniformity gave way to a significant divergence starting in 1987, with upper-tail (90/50) inequality rising steadily and lower tail (50/10) inequality either flattening or compressing for the next 16 years (1987 to 2003). This paper applies and extends a quantile decomposition technique proposed by Machado and Mata (2005) to evaluate the role of changing labor force composition (in terms of education and experience) and changing labor market prices to the expansion and subsequent divergence of upper- and lower-tail inequality over the last three decades We show that the extended Machado-Mata quantile decomposition corrects shortcomings of the original Juhn-Murphy-Pierce (1993) full distribution accounting method and nests the kernel reweighting approach proposed by DiNardo, Fortin and Lemieux (1996). Our analysis reveals that shifts in labor force composition have positively impacted earnings inequality during the 1990s. But these compositional shifts have primarily operated on the lower half of the earnings distribution by muting a contemporaneous, countervailing lower-tail price compression. The steady rise of upper tail inequality since the late 1970s appears almost entirely explained by ongoing between-group price changes (particularly increasing wage differentials by education) and residual price changes.

The Polarization of the U.S. Labor Market

This paper analyzes a marked change in the evolution of the U.S. wage structure over the past fifteen years: divergent trends in upper-tail (90/50) and lower-tail (50/10) wage inequality. We document that wage inequality in the top half of distribution has displayed an unchecked and rather smooth secular rise for the last 25 years (since 1980). Wage inequality in the bottom half of the distribution also grew rapidly from 1979 to 1987, but it has ceased growing (and for some measures actually narrowed) since the late 1980s. Furthermore we find that occupational employment growth shifted from monotonically increasing in wages (education) in the 1980s to a pattern of more rapid growth in jobs at the top and bottom relative to the middles of the wage (education) distribution in the 1990s. We characterize these patterns as the %u201Cpolarization%u201D of the U.S. labor market, with employment polarizing into high-wage and low-wage jobs at the expense of middle-wage work. We show how a model of computerization in which computers most strongly complement the non-routine (abstract) cognitive tasks of high-wage jobs, directly substitute for the routine tasks found in many traditional middle-wage jobs, and may have little direct impact on non-routine manual tasks in relatively low-wage jobs can help explain the observed polarization of the U.S. labor market.

Rising Wage Inequality: The Role of Composition and Prices

During the early 1980s, earnings inequality in the U. S. labor market rose relatively uniformly throughout the wage distribution. But this uniformity gave way to a significant divergence starting in 1987, with upper-tail (90/50) inequality rising steadily and lower tail (50/10) inequality either flattening or compressing for the next 16 years (1987 to 2003). This paper applies and extends a quantile decomposition technique proposed by Machado and Mata (2005) to evaluate the role of changing labor force composition (in terms of education and experience) and changing labor market prices to the expansion and subsequent divergence of upper- and lower-tail inequality over the last three decades We show that the extended Machado-Mata quantile decomposition corrects shortcomings of the original Juhn-Murphy-Pierce (1993) full distribution accounting method and nests the kernel reweighting approach proposed by DiNardo, Fortin and Lemieux (1996). Our analysis reveals that shifts in labor force composition have positively impacted earnings inequality during the 1990s. But these compositional shifts have primarily operated on the lower half of the earnings distribution by muting a contemporaneous, countervailing lower-tail price compression. The steady rise of upper tail inequality since the late 1970s appears almost entirely explained by ongoing between-group price changes (particularly increasing wage differentials by education) and residual price changes.

Peri-urbanisation, Social Heterogeneity and Ecological Simplification

Peri-urban development pressure on and near Australian coastlines is resulting in the conversion of agricultural land for rural-residential use. The impact of larger and more diverse human populations upon the ecological assets remaining in agricultural landscapes has consequently become a policy concern. This paper contributes to these policy debates by integrating the results of parallel social and ecological research projects commissioned to improve natural resource management in peri-urbanising regions. The research was undertaken in the case study region of South East Queensland, the region supporting Australia’s most rapid population growth. Our results indicate that both social and ecological communities cross a fragmentation threshold due to peri-urban development whereby they become ecologically simple and socially heterogeneous in a coupling that cedes a poor diagnosis for biodiversity retention.stored soil water, dryland grain cropping, extension, social systems, RD&E, differentiation

REM4j - A framework for measuring the reverse engineering capability of UML CASE tools

Reverse Engineering is becoming increasingly important in the software development world today as many organizations are battling to understand and maintain old legacy systems. Today’s software engineers have inherited these legacy systems which they may know little about yet have to maintain, extend and improve. Currently there is no framework or strategy that an organisation can use to determine which UML CASE tool to use. This paper sets down such a framework, to allow organisations to base their tool choice on this reliable framework. We present the REM4j tool, an automated tool, for benchmarking UML CASE tools, we then use REM4j to carry out one such evaluation with eleven UML CASE tools. This framework allows us to reach a conclusion as to which is the most accurate and reliable UML CASE tool

Education Reform and the Limits of Policy: Lessons from Michigan

By examining a major set of education policy reforms undertaken in Michigan and across the country over the past 20-plus years, Addonizio and Kearney are able to reveal the varying success of innovations such as finance reform, state assessment of student performance, school accountability measures, charter schools, and schools of choice.https://research.upjohn.org/up_press/1234/thumbnail.jp