Confidence regions for Pareto parameters from a single and independent samples

[Abstract] Based on a single and on two independent samples, joint confidence regions for parameters of Pareto distributions are proposed with minimum volume properties and without assigning the confidence level to dimensions. In the one-sample case, comparisons are made to former simultaneous confidence sets for Pareto parameters by means of simulation and a real data set. The two-sample case is studied in various set-ups and comprises simultaneous confidence regions for the shape parameters, the scale parameters, and higher-dimensional vectors of these parameters, where common shape and common scale models are also considered.     

The Use of Telematics Devices to Improve Automobile Insurance Rates

Most automobile insurance databases contain a large number of policyholders with zero claims. This high frequency of zeros may reflect the fact that some insureds make little use of their vehicle, or that they do not wish to make a claim for small accidents in order to avoid an increase in their premium, but it might also be because of good driving. We analyze information on exposure to risk and driving habits using telematics data from a pay‐as‐you‐drive sample of insureds. We include distance traveled per year as part of an offset in a zero‐inflated Poisson model to predict the excess of zeros. We show the existence of a learning effect for large values of distance traveled, so that longer driving should result in higher premiums, but there should be a discount for drivers who accumulate longer distances over time due to the increased proportion of zero claims. We confirm that speed limit violations and driving in urban areas increase the expected number of accident claims. We discuss how telematics information can be used to design better insurance and to improve traffic safety.     

Reducing management intensity and isolation as promising tools to enhance ground-dwelling arthropod diversity in urban grasslands

Urbanisation is a growing global phenomenon having multiple ecological consequences. However, the effects of urbanisation on biodiversity remain ambiguous, and some evidence exists that cities provide valuable secondary habitats for many species, possibly mitigating regional biodiversity loss. Therefore, the value of urban sites for biodiversity depends on local habitat conditions and the configuration of the surrounding landscape. We aimed to disentangle the effects of local habitat parameters (management, plant diversity) and urban matrix variables (urbanisation, isolation) on carabid beetle and spider diversity and traits in informal urban green spaces in Berlin, Germany. Habitat management and isolation were the most important influences on carabid beetle and spider species and trait compositions. Spider communities of irregular managed sites contained 2.5 times more species of conservation concern than extensive (regular) managed sites. Moreover, irregular managed sites contained larger species (both for carabid beetles and spiders) and affected the hunting mode of spiders. Isolated sites tended to have lower spider species richness and number of spider species of conservation concern. Moreover, isolated sites were characterised by small, mobile and herbivorous carabid beetles. In contrast, urbanisation and local plant diversity had no effect on carabid beetles and spiders. We conclude that urban grasslands within residential areas – even if not targeted for conservation plans – can provide important habitats for conserving biodiversity, including species of conservation concern. Reducing the intensity of habitat management and increasing the connectivity of urban grassland sites can promote diverse arthropod communities and should therefore be considered in urban planning.     

Führungsstile – Evaluation einer Nebenaufgabe im Development Center

To asses six different leadership styles we employed a questionnaire during the development center in a manufacturing firm. Analysing the questionnaire indicates its reliability, scalability, economy, usefulness and fairness. An explorative factor analysis supports the factorial validity. A content analysis provides evidence that the transformational leadership style is perceived as the most positive and the authoritarian leadership style as the most negative one. Furthermore, we found transformational leadership style positively correlated with an aggregated measure for the competence extraversion.     

Trend effects on perceived avalanche hazard

Hazard-level forecasts constitute an important risk mitigation tool to reduce loss of economic values and human life. Avalanche forecasts represent an example of this. As for many other domains, avalanche risk is communicated using a color-coded, categorical risk scale aimed at informing the public about past, current, and future risk. We report the results from three experiments in which we tested if an irrelevant past trend in forecasted avalanche danger affects perceptions of current and future avalanche risk. Our sample consisted of individuals from three different populations targeted by national avalanche warning services. All three experiments showed that the perception of avalanche risk is influenced by the trend, but that the effect is opposite for perceptions of current and expectations of future avalanche risk. While future avalanche risk is extrapolated in the same direction as the change from the previous day, we found that perceived current risk appears to be based on an average of past and current risk. These effects diminish when we provide participants with a scale indicating the exact level of avalanche danger. For most of our measurement instruments, however, the effects remain significant. These results imply that targeted populations may consider historic information more than was intended by the sender. As such, our results have implications for both avalanche warning services and risk communication in general.     

Nachhaltige Alltagsmobilit?t �� soziale Ungleichheiten und Milieus

Modern societies aremobile societies in a threefold aspect: socialmobility, international migrations and physical mobility (traffic). The article concentrates on the third, within sociological discourses more or less neglected aspect of mobility as physical mobility. From the perspective of sustainability and environment protection the production of greenhouse gases by individual motor car traffic is mostly debated resulting in reflections about alternative drive systems. In these debates social aspects of sustainable mobility are more or less neglected, partly as traditional mobility (system) research does not attach great importance to reflexive leeway. Based on recent studies the authors pick out two social aspects: unequal access to mobility systems as hardly any discussed aspect of social inequalities and the socio-cultural diversification alongside social milieus and lifestyles, which both are expressions and catalysts of (non-)sustainable forms of mobility.     

Severance Payments and Firm–specific Human Capital

What effect does employment protection through severance payments have on the behaviour of employed workers? We analyse this issue within a stochastic two–period framework where workers decide on human capital investments and find two competing effects: severance payments imply higher job security that fosters human capital formation. At the same time, a lay–off is perceived by the workers to be a weaker penalty if severance payments are provided. This incentive lowers their optimal amount of firm–specific investments. Which effect prevails on balance depends on the distribution of investment returns among firm and workers. For strong positive reactions, employment protection is also in the interests of the firm.     

A two-phase sampling scheme and πps designs

A two-phase approach for sampling with unequal inclusions probabilities and fixed sample size is presented. The expansion estimator using target inclusion probabilities is suggested for estimation of population parameters. As an alternative, the estimator for two-phase sampling can be used for estimation. Inclusion probabilities are shown to be asymptotically equivalent to the targeted inclusion probabilities. By means of simulation associated estimators are shown to work well with respect to bias and precision.     

Vertrauen als Merkmal von Beziehungsqualit?t: Modellentwicklung und explorative Interviews im Kontext sportpsychologischer Betreuung

A model is developed, defining interpersonal trust as the consequence of the individual??s evaluation concerning personal conditions and task conditions of counselling. Regarding evaluation, a situational, contextual, and global orientation is distinguished. Five expert-interviews are presented, aimed to test the structure and applicability of the given model in the practice. Goodwill and esteem for the athlete, both situational and contextual connected, were stressed by the experts as important for trust building so as the attribution of a trustful personality was. The interviewed experts ranked expertness as a factor of lower significance for trust building. Discrepancies between the theoretical model and the experts?? opinion refer to future research and opportunities to optimize counselling.