Semi-Daily Journal Archive

The Blogspot archive of the weblog of J. Bradford DeLong, Professor of Economics and Chair of the PEIS major at U.C. Berkeley, a Research Associate of the National Bureau of Economic Research, and former Deputy Assistant Secretary of the U.S. Treasury.

Monday, August 21, 2006

The Rise in U.S. Inequality: What the Labor-Side Real Professionals Say

Greg Mankiw wrote: "Policy choices such as tax rates and minimum wages have not been the main causes of increasing inequality. At least that is the consensus, as I understand it, of the professional labor economists who study the issue."

That overstates it a bit, I think. The real professional labor economists argue. And my perspective--here in Berkeley under the intellectual hegemony of the terrifyingly brilliant David Card--is that the real professionals are arguing fiercely.

Here are some of their recent contributions:

Unionization and Wage Inequality: A Comparative Study of the U.S, the U.K., and Canada: David Card, Thomas Lemieux, W. Craig Riddell: This paper presents a comparative analysis of the link between unionization and wage inequality in the U.S., the U.K., and Canada. Our main motivation is to see whether unionization can account for differences and trends in wage inequality in industrialized countries. We focus on the U.S., the U.K., and Canada because the institutional arrangements governing unionization and collective bargaining are relatively similar in these three countries. The three countries also share large non-union sectors that can be used as a comparison group for the union sector. Using comparable micro data for the last two decades, we find that unions have remarkably similar qualitative impacts in all three countries. In particular, unions tend to systematically reduce wage inequality among men, but have little impact on wage inequality for women. We conclude that unionization helps explain a sizable share of cross-country differences in male wage inequality among the three countries. We also conclude that de-unionization explains a substantial part of the growth in male wage inequality in the U.K. and the U.S. since the early 1980s.

Skill Biased Technological Change and Rising Wage Inequality: Some Problems and Puzzles: David Card, John E. DiNardo: The rise in wage inequality in the U.S. labor market during the 1980s is usually attributed to skill-biased technical change (SBTC), associated with the development of personal computers and related information technologies. We review the evidence in favor of this hypothesis, focusing on the implications of SBTC for economy-wide trends in wage inequality, and for the evolution of wage differentials between various groups. A fundamental problem for the SBTC hypothesis is that wage inequality stabilized in the 1990s, despite continuing advances in computer technology. SBTC also fails to explain the closing of the gender gap, the stability of the racial wage gap, and the dramatic rise in education-related wage gaps for younger versus older workers. We conclude that the SBTC hypothesis is not very helpful in understanding the myriad shifts in the structure of wages that have occurred over the past three decades.

The Polarization of the U.S. Labor Market: David H. Autor, Lawrence F. Katz, Melissa S. Kearney: 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 “polarization” 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: David H. Autor, Lawrence F. Katz, Melissa S. Kearney: 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-M

urphy-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. >[Trends in U.S. Wage Inequality: Re-Assessing the Revisionists](http://papers.nber.org/papers/w11627): David H. Autor, Lawrence F. Katz, Melissa S. Kearney: 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. It's a four-sided cage match between technology, globalization, sociology, and public policy.

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