Unions and innovative activity in Germany

This study is the first attempt to investigate the influence of unions on innovative activities in Germany at the industry level. Econometric models estimated by a highly robust method and submitted to a number of specification tests indicate that trade unions do not have a negative impact on innovative activity which is measured by either the percentage of revenues spent on R&D or the percentage of employees working in R&D. This finding is consistent with evidence on the influence of unions on productivity in Germany and with considerations about the German system of industrial relations.     

Schulverweigerung

The aim of this article is to describe the extent of truancy in Cologne and to identify the relevant predictors. Hypotheses are deduced from classical deviance theories (control theory, amomy theory, theory of urban subcultures) and tested empirically. Our analysis is based on a survey of pupils in Cologne from grade 8 to 10 which was conducted in 1999 by the Max Planck Institute for Foreign and International Criminal Law in Freiburg. Our results show that 7.9 percent of all respondends can be defined as truants. Boys play truant more than girls, and the higher the age, the more pupils bunk off school. More important than gender and age is the type of secondary school. We find the highest amount of truants at Hauptschulen and Sonderschulen. It is shown that truancy is a multidimensional phenomenon that cannot be explained by just one single theory.     

Numerical solution of optimal allocation problems in stratified sampling under box constraints

Modern sampling designs in survey statistics, in general, are constructed in order to optimize the accuracy of estimators such as totals, means and proportions. In stratified random sampling a variance minimal solution was introduced by Neyman and Tschuprov. However, practical constraints may lead to limitations of the domain of sampling fractions which have to be considered within the optimization process. Special attention on the complexity of numerical solutions has to be paid in cases with many strata or when the optimal allocation has to be applied repeatedly, such as in iterative solutions of stratification problems. The present article gives an overview of recent numerical algorithms which allow adequate inclusion of box constraints in the numerical optimization process. These box constraints may play an important role in statistical modeling. Furthermore, a new approach through a fixed point iteration with a finite termination property is presented.     

Modelling of a thermomechanically coupled forming process based on functional outputs from a finite element analysis and from experimental measurements

In this paper, measurements from experiments and results of a finite element analysis (FEA) are combined in order to compute accurate empirical models for the temperature distribution before a thermomechanically coupled forming process. To accomplish this, Design and Analysis of Computer Experiments (DACE) is used to separately compute models for the measurements and the functional output of the FEA. Based on a hierarchical approach, a combined model of the process is computed. In this combined modelling approach, the model for the FEA is corrected by taking into account the systematic deviations from the experimental measurements. The large number of observations based on the functional output hinders the direct computation of the DACE models due to the internal inversion of the correlation matrix. Thus, different techniques for identifying a relevant subset of the observations are proposed. The application of the resulting procedure is presented, and a statistical validation of the empirical models is performed.     

Mental Models of Flash Floods and Landslides

Perceptions of flash floods and landslides were analyzed in four communities of the Bavarian Alps using the mental model approach. Thirty-eight qualitative interviews, two telephone surveys with 600 respondents, and two onsite interviews (74/95 respondents) were conducted. Mental models concerning flash floods are much better developed than those for landslides because the key physical processes for flash floods are easier for the general public to recognize and understand. Mental models are influenced by the local conditions. People who have a better knowledge about the hazards are those who use many different sources to inform themselves, express fear about natural hazards, or have previous experience with hazards. Conclusions for how to improve information for the general public are discussed.