Comments on goodness-of-fitmeasures in binary choice models by frank windmeijer

Why study Pseudo-R²,s for limited dependent variable models? After all, even in the much clearer ordinary least squares case, R² is a poor guide to model selection, at least when used by itself, because it never decreases and typically increases whenever an independent variable is added. There are even cases where R² will tend to one when there is no relationship among the (nonstationary) variables whatsoever (Granger and Newbold, 1974). Surely applied researchers would not want to bother with such a statistic in the limited dependent variable case, particularly when the intuitive explainedvariation- to- total- variation interpretation is no longer available.     

Normal random numbers lying on spirals and clubs

Two methods for transforming uniformly distributed random numbers into normally distributed random numbers are considered in conjunction with linear congruential generators. The two-dimensional lattice structure of the uniform random numbers is transformed by the Box-Muller method into a spiral structure and by the polar method into a club-shaped structure. The approximation of the two-dimensional normal distribution and the independence of the associated random variables are discussed.     

Pflege der Eltern – Ein europäischer Vergleich*

Elderly people are predominantly cared for by family members. However, not every parent in need is cared for by a child, and not all family members are involved in care. Which factors influence the provision of care? Do European countries differ in regard to intergenerational care, and what are the reasons for these differences? The empirical analyses, based on the Survey of Health, Ageing and Retirement in Europe (Austria, Belgium, Denmark, France, Germany, Greece, Italy, the Netherlands, Spain, Sweden, and Switzerland), show that various factors influence care by children: individual characteristics of parents and children, family structures and cultural-contextual factors, including welfare institutions. Intergenerational help occurs more often in Southern and Central European countries, where children are legally obliged to support parents in need. At the same time, in Europe professional home care services enable adult children to pursue their personal plans beyond care obligations.     

Elbow torque ellipses: investigation of the mutual influences of rotation, flexion, and extension torques

Most strength tests are restricted to measuring joint torques only in main directions like flexion or pronation. However, for an advanced strength prediction model, information about maximum possible joint torques in intermediate directions also has to be known. This paper concentrates on obtaining functions for maximum joint torques in arbitrary directions in the elbow. Therefore, isometric joint torque measurements have been conducted with 20 young males applying joint torques in eight different directions in one posture (90 degrees elbow flexion, 0 degrees shoulder flexion, neutral forearm rotation). It turns out that the appearance of the resulting shape can be best predicted using ellipse segments. Furthermore, a standardized ellipse could be obtained for the measurement posture. This helps to predict maximum joint torques in any other direction by knowing only one of the main joint torques.     

„Anders denken,anders fühlen“. Klaus Doppler über Erbe und Zukunft des Change Managements

Gruppe. Interaktion. Organisation. Zeitschrift für Angewandte Organisationspsychologie (GIO) - Klaus Doppler führte das Konzept Change Management im deutschsprachigen Bereich ein. Er...     

Ethnic identity and the choice to play for a national team: a study of junior elite football players with a migrant background

In German (junior) elite football, there are a comparatively large number of highly talented players with a migrant background. These players were born in Germany and joined the Talent Development Programme of the German Football Association (DFB). Many of these players can decide for which national association they want to play in international games. In media and public discourse, this decision is usually explained by the degree of self-identification with a specific ethnic group. However, this assumption is not empirically evident. Using the example of junior elite players with a Turkish background, this article focuses therefore on the question, which role ethnic identity plays in this decision. Based on social identity theory, we conducted semi-structured interviews with 10 adolescent elite football players with Turkish background who played for the German and/or the Turkish Football Association. Our findings suggest that – in contrast to media narratives – ethnic identity only plays a marginal role in the decision to play for a national football association.     

Connectivity of public urban grasslands: implications for grassland conservation and restoration in cities

An important limitation of studies on the ecological value of urban habitats is the question of habitat connectivity. While connectivity allows spread and genetic exchange of species, isolation can lead to the extinction of populations through inbreeding and loss of genetic diversity. However, while practitioners already start improving urban habitat patches by means of restoration, issues of connectivity have not been taken in account although being crucial for a self-sustaining habitat network. In our study, we evaluate the connectivity of public urban grasslands such as lawns, grasslands in residential areas, playgrounds or parks in the city of Münster, Germany. Employing a graph theory approach, which uses a map (graph) of habitat patches to calculate functional connectivity measures using patch area size and patch connectivity, we studied four groups of different plant dispersal distances (2 m, 20 m, 44 m and 100 m). This approach can be recommended for planning issues due to the output of different indicator values and comparably low data demands. Our results show for the first time, that connectivity of urban grasslands is extremely low for species of short-distance dispersal but slightly increases for long-distance dispersal. Except two larger conglomerations of well-connected patches, urban grasslands were found to be mostly sparsely connected. Thus, future research should focus on options to improve connectivity and to prioritize patches for ecological improvement. The graph theory approach turned out to be a useful tool to analyse urban habitat connectivity but also to illustrate results obtained.