Iterative regularisation in nonparametric instrumental regression

This paper considers the nonparametric regression model with an additive error that is correlated with the explanatory variables. Motivated by empirical studies in epidemiology and economics, it also supposes that valid instrumental variables are observed. However, the estimation of a nonparametric regression function by instrumental variables is an ill-posed linear inverse problem with an unknown but estimable operator. We provide a new estimator of the regression function that is based on projection onto finite dimensional spaces and that includes an iterative regularisation method (the Landweber–Fridman method). The optimal number of iterations and the convergence of the mean square error of the resulting estimator are derived under both strong and weak source conditions. A Monte Carlo exercise shows the impact of some parameters on the estimator and concludes on the reasonable finite sample performance of the new estimator.     

The economic evaluation of a Participatory Ergonomics programme to prevent low back and neck pain

This study was an economic evaluation conducted alongside a cluster randomised controlled trial with a follow-up of 12 months. The aim was to evaluate the cost-effectiveness and cost-benefit of the Stay@Work Participatory Ergonomics programme (PE) compared to a control group (no PE). In total, 37 departments (n=3047 workers) were randomised into either the intervention (PE) or control group (no PE). During a meeting, working groups followed the steps of PE, and composed and prioritized ergonomic measures aimed to prevent low back pain (LBP) and neck pain (NP). Working groups had to implement the ergonomic measures within three months in their department. Cost data included those directly related to LBP and NP. Cost-effectiveness analyses (CEA) and cost-benefit analyses (CBA) were performed. After 12 months, health care costs and costs of productivity losses were higher in the intervention group than in the control group (the mean total cost difference was $/euro$127; 95% CI $/euro$-164 - $/euro$418). From a societal perspective, the CEA showed that PE was not cost-effective compared to control for LBP and NP prevalence, work performance, and sick leave. The CBA from a company perspective showed a monetary loss of $/euro$78 per worker. The PE programme was neither cost-effective nor cost-beneficial on any of the effect measures.     

Wage Dynamics and Unemployment in Germany: Evidence from Regional Panel Data

A stylized fact of empirical work on the relationship of wages and unemployment using macro data for European countries is a combination of strong autocorrelation of wages and a significant negative long‐run relationship of wages and unemployment. However, this view is challenged by empirical work relying on regional or micro data providing evidence for an instantaneous adjustment of wages to variations in the level of unemployment. Exploiting regional panel data for West Germany, we show that, at least for the years 1990–94, regional and macro data mirror the same phenomenon. Our results are broadly consistent with the observed increase in the natural rate of unemployment in Germany.     

Inequality-minimization with a given public budget

We solve the problem of a social planner who seeks to minimize inequality via transfers with a fixed public budget in a distribution of exogenously given incomes. The appropriate solution method depends on the objective function: If it is convex, it can be solved by an interior-point algorithm. If it is quasiconvex, the bisection method can be used. Using artificial and real-world data, we implement the procedures and show that the optimal transfer scheme need not comply with a transfer scheme that perfectly equalizes incomes at the bottom of the distribution.     

Using Mokken methods to develop robust cross-national scales: American and West German attitudes toward abortion

A fundamental methodological issue in cross-national research on attitudes is the comparability of the attitude measures across populations. We address this issue by presenting the Mokken method and accompanying Mokken test as a means for developing equivalent attitude scales. We apply these methods to an analysis of the responses to seven abortion items in the 1982 NORC GSS and West German ALLBUS combined files. We find that the seven items form a unidimensional scale in both countries and that four of these items constitute a scale that is robust across the two populations. We conclude by describing how such results can be used to guide the development of Rasch and LISREL models.     

The Immigrant Wage Gap in Germany: Are East Europeans Worse Off?

Using employment register data, this study compares the outcomes of male foreign workers from different East and West European countries who entered the German labor market between 1995 and 2000 with those of male German workers. Although the wage differentials are highest for Poles, results from Oaxaca/Blinder type decompositions show that the East Europeans are not generally worse off. Actually, we find considerable heterogeneity also within nationality groups. Quantile decompositions show that coefficients effects tend to be larger at the bottom of the wage distribution and, by that, give evidence for sticky floors.     

Economic growth and social capital: A critical reflection

Theory and Society -     

Prevalence of technology-intensive international alliances

A population perspective of the formation, long-term survival, and prevalence of U.S./Japanese alliances in seven technology-intensive areas suggests the presence of two subpopulations. We have called these two subpopulations dominated and hybridized. They were predicted and empirically identified as being comprised of unique combinations of the technical area of operations, the administrative form of the alliance, and the product/knolwedge flow through the entity.