Bernd Fitzenberger

The Moving Blocks Bootstrap and Robust Inference for Linear Least Squares and Quantile Regressions

Abstract This paper presents the moving blocks bootstrap (MBB) as a new inference procedure for linear regression estimation which is robust to heteroskedasticity and autocorrelation of unknown forms. The MBB covariance estimator is shown to provide heteroskedasticity and autocorrelation consistent (HAC) standard errors for least squares (LS) and quantile regression (QR) coefficient estimators. The MBB covariance estimator is shown to be asymptotically equivalent to the Bartlett kernel estimator suggested by Newey and West (1987) and the asymptotically optimal choice of the blocksize is discussed. A Monte Carlo study is included showing that the MBB fares well in comparison to standard HAC inference procedures. Considering strong mixing data generating processes, the paper extends existing asymptotic results for the QR estimator. The analogy to the LS case is stressed. The paper analyzes both the cases of stochastic and of nonstochastic regressors and suggests two new Grenander-like conditions for the latter case. The use of the MBB approach is illustrated for a practical example using a standard econometric package.

Rising Wage Inequality, the Decline of Collective Bargaining, and the Gender Wage Gap

This paper investigates the increase in wage inequality, the decline in collective bargaining, and the development of the gender wage gap in West Germany between 2001 and 2006. Based on detailed linked employer-employee data, we show that wage inequality is rising strongly – driven not only by real wage increases at the top of the wage distribution, but also by real wage losses below the median. Coverage by collective wage bargaining plummets by 16.5 (19.1) percentage points for male (female) employees. Despite these changes, the gender wage gap remains almost constant, with some small gains for women at the bottom and at the top of the wage distribution. A sequential decomposition analysis using quantile regression shows that all workplace related effects (firm effects and bargaining effects) and coefficients for personal characteristics contribute strongly to the rise in wage inequality. Among these, the firm coefficients effect dominates, which is almost exclusively driven by wage differences within and between different industries. Labor demand or firm wage policy related effects contribute to an increase in the gender wage gap. Personal characteristics tend to reduce wage inequality for both, males and females, as well as the gender wage gap.

Get Training or Wait? Long-Run Employment Effects of Training Programs for the Unemployed in West Germany

Long-term public sector sponsored training programs often show little or negative short-run employment effects and often it is not possible to assess whether positive long-run effects exist. Based on unique administrative data, this paper estimates the long-run differential employment effects of three different types of training programs in West Germany. We use inflows into unemployment for the years 1986/87 and 1993/94 and apply local linear matching based on the estimated propensity score to estimate the effects of training programs starting during 1 to 2, 3 to 4, and 5 to 8 quarters of unemployment. The results show a negative lock-in effect for the period right after the beginning of the program and significantly positive treatment effects on employment rates in the medium- and long-run. The differential effects of the three programs compared to one another are mainly driven by differences in the length of the lock-in periods.

Unemployment Durations in West Germany Before and after the Reform of the Unemployment Compensation System During the 1980s

This paper empirically analyzes the distribution of unemployment durations in West Germany before and after the changes during the mid 1980s in the maximum entitlement periods for unemployment benefits for elderly unemployed. The analysis is based on the comprehensive IAB employment subsample containing register panel data for about 500,000 individuals in West Germany. We introduce two proxies for unemployment, since the data do not involve a precise economic definition of unemployment. We provide a theoretical analysis of the link between the durations of nonemployment and of unemployment durations between jobs. In our empirical analysis we find significant changes in the distributions of nonemployment durations for older unemployed individuals. At the same time, the distribution of unemployment durations between jobs did not change in response to the reforms. Our findings are consistent with an interpretation that many firms and workers used the more beneficial laws as a part of early retirement packages but those workers who were still looking for a job did not reduce their search effort in response to the extension of the maximum entitlement periods. This interpretation is consistent with a simulation of our theoretical model under economically plausible assumptions.

Gender Wage Differences in West Germany: A Cohort Analysis

A comprehensive descriptive analysis of gender wage differences over a long time period is missing for West Germany. Using an empirical approach which takes into account explicitely changes of wage distributions for both males and females as well as life-cycle and birth cohort effects, we go beyond conventional decomposition techniques of the average gender wage gap. The paper provides some stylized facts of the level and dynamics of the gender wage gap from 1975 - 1995. The empirical analysis is based upon the IAB-Beschaftigtenstichprobe. Our findings confirm the importance of distributional effects relating to skill level and employment status. While life-cycle wage growth is in general much lower for females compared to males, comparing their estimated time trends implies that the gender wage gap has narrowed substantially in the lower part of the wage distribution especially for low-and medium-skilled females but much less so in the upper part of the wage distribution. Surprisingly, we do not find any cohort effects for wages of female employees.

Union Density and Varieties of Coverage: The Anatomy of Union Wage Effects in Germany

Collective bargaining in Germany takes place either at the industry level or at the firm level; collective bargaining coverage is much higher than union density; and not all employees in a covered firm are necessarily covered. This institutional setup suggests to explicitly distinguish union power as measured by net union density (NUD) in a labor market segment, coverage at the firm level, and coverage at the individual level. Using linked employer-employee data and applying quantile regressions, this is the first empirical paper which simultaneously analyzes these three dimensions of union influence on the structure of wages. Ceteris paribus, a higher share of employees in a firm covered by industry-wide or firm-level contracts is associated with higher wages. Yet, individual bargaining coverage in a covered firm shows a negative impact both on the wage level and on wage dispersion. A higher union density reinforces the effects of coverage, but the effect of union density is negative at all points in the wage distribution for uncovered employees. In line with an insurance motive, higher union density compresses the wage structure and, at the same time, it is associated with a uniform leftward movement of the distribution for uncovered employees.

Can a Task-Based Approach Explain the Recent Changes in the German Wage Structure?

Summary This paper investigates the changes in the German wage structure for full-time working males from 1999 to 2006. Our analysis builds on the task-based approach introduced by Autor et al. (2003), as implemented by Spitz-Oener (2006) for Germany, and also accounts for job complexity. We perform a Blinder-Oaxaca type decomposition of the changes in the entire wage distribution between 1999 and 2006 into the separate effects of personal characteristics and task assignments. In line with the literature, we find a noticeable increase of wage inequality between 1999 and 2006. The decomposition results show that the changes in personal characteristics explain some of the increase in wage inequality whereas the changes in task assignments strongly work towards reducing wage inequality. The coefficient effect for personal characteristics works towards an increase in wage inequality at the top of the wage distribution. The coefficient effect for the task assignments on the contrary shows an inverted U-shaped pattern. We conclude that altogether the task-based approach can not explain the recent increase of wage inequality in Germany.

Industry-Level Wage Bargaining: A Partial Rehabilitation - The German Experience

In order to reduce unemployment, it is often recommended that industry-level wage bargaining in Germany should be replaced by a more decentralized system. This paper provides a critical assessment of the current wage bargaining institutions and reexamines the case for a more decentralized system. Based on a theoretical model integrating Insider-Outsider aspects into the comparison, the unformly superior employment performance of a decentralized wage bargaining system is questioned. We conclude that, rather than solely trying to decentralize wage bargaining, a promising policy option may be to improve the skills of the unemployed by efficient labour market policies and to foster institutional reforms such that wage bargaining takes account of the long-run employment consequences of wage setting.

Polarization and rising wage inequality : comparing the U.S. and Germany

This paper compares trends in wage inequality in the U.S. and Germany using an approach developed by MaCurdy and Mroz (1995) to separate age, time, and cohort effects. Between 1979 and 2004, wage inequality increased strongly in both the U.S. and Germany but there were various country specific aspects of this increase. For the U.S., we find faster wage growth since the 1990s at the top (80% quantile) and the bottom (20% quantile) compared to the median of the wage distribution, which is evidence for polarization in the U.S. labor market. In contrast, we find little evidence for wage polarization in Germany. Moreover, we see a large role played by cohort effects in Germany, while we find only small cohort effects in the U.S. Employment trends in both countries are consistent with polarization since the 1990s. We conclude that although there is evidence in both the U.S. and Germany which is consistent with a technology-driven polarization of the labor market, the patterns of trends in wage inequality differ strongly enough that technology effects alone cannot explain the empirical findings.

Economic Applications of Quantile Regression

Individual heterogeneity in the returns to schooling: instrumental variables quantile regression using twins data.- Testing for uniform wage trends in West-Germany: A cohort analysis using quantile regressions for censored data.- Quantile regression with sample selection: Estimating womens return to education in the U.S..- Earning functions in Portugal 1982-1994: Evidence from quantile regressions.- Wage inequality in a developing country: decrease in minimum wage or increase in education returns.- How wide is the gap? An investigation of gender wage differences using quantile regression.- The public-private sector wage gap in Zambia in the 1990s: A quantile regression approach.- Asymmetric labor supply.- Quantile regression for duration data: A reappraisal of the Pennsylvania Reemployment Bonus Experiments.- For whom the reductions count: A quantile regression analysis of class size and peer effects on scholastic achievement.- The effects of demographics and maternal behavior on the distribution of birth outcomes.- Nonparametric quantile regression analysis of R & D-sales relationship for Korean firms.- Conditional value-at-risk: Aspects of modeling and estimation.- Portfolio style: Return-based attribution using quantile regression.- Integrated Conditional Moment testing of quantile regression models.