Re-evaluating the Community Question from a German perspective

The far-reaching effects of the social systemic division of labor on the organization and contents of primary ties make the Community Question an important issue for many sociologists. This paper looks at the personal embeddedness of families in three German cities (Berlin, Hamburg, and Stuttgart) and examines the Community Question with data collected at the end of 2003. It is based on the theoretical views of Wellman [Wellman, B., 1979. The community question. The intimate networks of East Yorkers. American Journal of Sociology 84, 1201–1231], who used a network analysis perspective to conceptualize “the Community Question”. The results of this German study generally support the results of Wellman's second East York Study. However, the network structures analyzed in my study vary from the three ideal-type models. Cluster analysis shows that Wellman's typology can be replicated relatively well in Germany. In contrast to traditional discourse related to the Community Question, particular network types are not associated with low levels of social relations. Moreover, structural factors do not explain the existence of different network types. Thus, the networks are not a product of only one community model. They suggest that it is less helpful to talk about “Saved”, “Lost”, or “Liberated” communities than it is to regard communities as a mixture of strongly-knit nuclear clusters and of broader, sparsely-knit relations that provide access to different groups and their resources.     

Probabilistic linear solvers: a unifying view

Statistics and Computing - Several recent works have developed a new, probabilistic interpretation for numerical algorithms solving linear systems in which the solution is inferred in a Bayesian...     

Probabilistic solutions to ordinary differential equations as nonlinear Bayesian filtering: a new perspective

Statistics and Computing - We formulate probabilistic numerical approximations to solutions of ordinary differential equations (ODEs) as problems in Gaussian process (GP) regression with nonlinear...     

Families and their Social Relations in German Cities

This paper looks at the personal embeddedness of families in three German cities (Berlin, Hamburg, Stuttgart) and examines the community question with data collected at the end of 2003. The study is based on the theoretical views of Barry Wellman, who used a network analysis perspective to conceptualize ‘the Community Question’. The results of the German study have reconfirmed the results of Wellman's East York Study and show that networks are not a product of only one community model. As a consequence it is less helpful to talk about saved, lost and liberated communities but more helpful to regard communities as a mixture of strongly knitted nuclear clusters and broader sparsely knitted relations which have access to different groups and their resources. Most networks consist of kinship, friends, local and long distance ties, multistranded and specialised ties. The current analysis of the data of this study indicates that in German cities there is no correlation between the different distributions of the community.     

The Clustering of Categorical Data: A Comparison of a Model-based and a Distance-based Approach

For clustering multivariate categorical data, a latent class model-based approach (LCC) with local independence is compared with a distance-based approach, namely partitioning around medoids (PAM). A comprehensive simulation study was evaluated by both a model-based as well as a distance-based criterion. LCC was better according to the model-based criterion and PAM was sometimes better according to the distance-based criterion. However, LCC had an overall good and sometimes better distance-based performance as PAM, although this was not the case in a real data set on tribal art items.     

Pollinating animals in the urban environment

Urban environments contain habitats for flowering plants and their pollinating animal species. It is, however, unclear how the urban matrix influences plant-pollinator processes. We recorded plant diversity, floral abundance, flower visitor diversity and plot visits at 89 plant patches within the city of Zürich. The urban matrix surrounding each site was analyzed for the landscape metrics edge density and the extent of green area up to 200 m radius. The correlation between edge density and bee diversity and visitation frequency varied over the entire spatial range, while the correlation for syrphid diversity and visitation frequency levelled off at 80 m radius. In contrast, the correlations with green area were more consistent, with bee diversity levelling off after 100 m, while syrphid diversity and visits continued to increase. The variation in the correlation of bee visits was partly accounted for by the large contribution of honeybees. Plant diversity significantly affected bee diversity and visits, and syrphid visits. Floral abundance had a positive effect on bee visits and bee diversity. Syrphid diversity had a negative interaction with floral abundance and green area. The extent of green area increased bee diversity and visits, and syrphid visits, while edge density reduced visitation by bees. This study showed that plant diversity and floral abundance in urban environments promote pollinating flower visitors. The extent of green area and edge density are important urban mosaic attributes that affect pollinator abundance and visitation frequency at multiple scales.     

In Search of Workers' Real Effort Reciprocity—a Field and a Laboratory Experiment

We present a field experiment to assess the effect of own and peer wage variations on actual work effort of employees with hourly wages. Work effort neither reacts to an increase of the own wage, nor to a positive or negative peer comparison. This result seems at odds with numerous laboratory experiments that show a clear own wage sensitivity on effort. In an additional real‐effort laboratory experiment we show that explicit cost and surplus information that enables an exact calculation of an employer's surplus from the work contract is a crucial prerequisite for a positive wage–effort relation. This demonstrates that an employee's reciprocity requires a clear assessment of the surplus at stake. (JEL: C91, C92, J41)     

冬季花仙子——梅花

我和两个哥哥一起在特斯特汉长大，这是位于路易斯安那州的一个偏僻小镇，一个很好的地方——这儿的人们都很脚踏实地。尽管如此，我却总是梦想着能够去纽约跳舞。还在穿尿布的时候我就开始跳舞了，所以我总是想着有一天能登上百老汇的舞台。     

Comparing clusterings and numbers of clusters by aggregation of calibrated clustering validity indexes

Statistics and Computing - A key issue in cluster analysis is the choice of an appropriate clustering method and the determination of the best number of clusters. Different clusterings are optimal...