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Social capital covers different characteristics such as social networks, social participation, social support and trust. The aim of this study was to explore which aspects of social capital were predictive of mortality. Criteria for inclusion in the meta-analysis were: population based observational cohort studies (follow-up ≥5 years); study sample included the adult population; parts of social capital as the primary exposure variable of interest; reported a mortality outcome; and sample size >1,000 individuals. Twenty studies provided eligible data for the meta-analyses. A random effect model was used to estimate the combined overall hazard rate ratio effects of structural social capital such as social participation and social networks, and cognitive social capital including social support and trust in relation to mortality. The results showed that social participation and social networks were negatively associated with mortality. The impact of social networks attenuated somewhat when controlling for gender and age. While trust also appeared to be negatively associated with mortality, we remain cautious with this conclusion, since only two studies provided eligible data. Perceived social support failed to show a significant impact upon mortality. The findings suggest that people who engage socially and report frequent contacts with friends and family live longer.  相似文献   
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Although of considerable practical importance, the separate impact of individual and collective reputation on firm performance (e.g. product prices) has not yet been convincingly demonstrated. We use a sample of some 70 different wineries offering more than 1,300 different Riesling wines from the Mosel valley to isolate the returns to individual reputation (measured by expert ratings in a highly respected wine guide) from the returns to collective reputation (measured by membership in two different professional associations where members are assumed to monitor each other very closely). We find that both effects are statistically significant and economically relevant with the latter being more important in quantitative terms than the former.  相似文献   
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In most West European economies the annual number of grievance procedures settling individual complaints against unfair dismissals has been increasing since the 1960s. This development has very often been attributed to the enactment of legal regulations restricting the dismissal behaviour of firms. Econometric analyses using data from Germany and Great Britain show that labour market developments, namely the flow into unemployment and the vacancy rate, have a much stronger influence on the cyclical demand for grievance procedures than changes in the “legal infrastructure” of the labour market. Without denying the importance of institutional differences it appears that the individual costs of unemployment (which, ceteris paribus, rise as the flow into unemployment increases and the vacancy rate decreases) are superior predictors of the demand for grievance procedures than institutional changes strengthening or weakening employees' rights.  相似文献   
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Bernd Lisek 《Statistics》2013,47(4):561-581
A stationary state distribution will be constructed for a loss system G/G/m/0 without additional restrictive conditions. It will be shown by examples that for a given input there may exist several stationary state distributions. A sufficient and necessary criterion for the uniqueness will be formulated.  相似文献   
46.
The results of analyzing experimental data using a parametric model may heavily depend on the chosen model for regression and variance functions, moreover also on a possibly underlying preliminary transformation of the variables. In this paper we propose and discuss a complex procedure which consists in a simultaneous selection of parametric regression and variance models from a relatively rich model class and of Box-Cox variable transformations by minimization of a cross-validation criterion. For this it is essential to introduce modifications of the standard cross-validation criterion adapted to each of the following objectives: 1. estimation of the unknown regression function, 2. prediction of future values of the response variable, 3. calibration or 4. estimation of some parameter with a certain meaning in the corresponding field of application. Our idea of a criterion oriented combination of procedures (which usually if applied, then in an independent or sequential way) is expected to lead to more accurate results. We show how the accuracy of the parameter estimators can be assessed by a “moment oriented bootstrap procedure", which is an essential modification of the “wild bootstrap” of Härdle and Mammen by use of more accurate variance estimates. This new procedure and its refinement by a bootstrap based pivot (“double bootstrap”) is also used for the construction of confidence, prediction and calibration intervals. Programs written in Splus which realize our strategy for nonlinear regression modelling and parameter estimation are described as well. The performance of the selected model is discussed, and the behaviour of the procedures is illustrated, e.g., by an application in radioimmunological assay.  相似文献   
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Zusammenfassung: Im Rahmen seiner industrie?konomischen Forschung beabsichtigt das DIW Berlin das Verhalten von Unternehmen auf den Produktm?rkten intensiver zu analysieren. In einem ersten Schritt soll der Zusammenhang zwischen Produktdiversifizierung, der Einführung neuer Produkte und dem Erfolg von Unternehmen im verarbeitenden Gewerbe untersucht werden. Dies soll mit Hilfe einer ?konometrischen Panelanalyse auf der Grundlage von Mikrodaten von Unternehmen erfolgen. Statt des in der Arbeitsmarktforschung üblichen Employer-Employee Datensatzes wird für diesen Zweck ein Producer-Product Datensatz ben?tigt. Erstmals sollen diese Mikrodaten im Rahmen einer Panelanalyse durch die Forschung ausgewertet werden. Dabei werden zwei getrennt durchgeführte Erhebungen, die Kostenstrukturerhebung und die Produktionserhebung, für einzelne Unternehmen zusammengefasst. M?glich wird dieses Forschungsvorhaben durch die Nutzung des auf Empfehlung der Kommission zur Verbesserung der informationellen Infrastruktur neu eingerichteten Forschungsdatenzentrums (FDZ). Das vorliegende Papier berichtet über das Forschungskonzept und die bisher erfolgten Schritte bei der Nutzung der Forschungsdatenzentren des Bundes und der L?nder am regionalen Standort Berlin.
Summary: For a better understanding of the strategies of firms on their product markets, the DIW Berlin intends to intensify the analysis on the relationship between product diversification, including the introduction of new products and the success of firms. It is planned to do this by applying econometric panel methods on micro level data for German manufacturing enterprises. For this objective, it is necessary to create a producer-product database. This affords the merging of two different datasets of the system of surveys in manufacturing for Germany. The cost structure survey supplies information on the operating surplus of individual firms, while the production survey supplies the information on the goods produced by these firms. Conducting such an ambitious project has now been made possible in using the newly installed Research Data Centres (FDZ) for Germany. This paper gives an overview on the research project and on first experiences with the use of the local Research Data Centre in Berlin.
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49.
    
R is a multi-paradigm language with a dynamic type system, different object systems and functional characteristics. These characteristics support the development of statistical algorithms at a high level of abstraction. Although R is commonly used in the statistics domain a big disadvantage are its runtime problems when handling computation-intensive algorithms. Especially in the domain of machine learning the execution of pure R programs is often unacceptably slow. Our long-term goal is to resolve these issues and in this contribution we used the traceR tool to analyse the bottlenecks arising in this domain. Here we measured the runtime and overall memory consumption on a well-defined set of classical machine learning applications and gained detailed insights into the performance issues of these programs.  相似文献   
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