A simplified algorithm for the depot location problem

This paper describes a simplified optimization algorithm used for the solution of a classical depot location problem as presented in a Greek Manufacturing Company. Algorithms in the literature for this type of problem are based on the assumption of predetermined fixed costs which are independent of the final size of the depots. This assumption is usually far from reality; the size of each depot does not remain constant during the optimization process and so does the associated fixed cost which is variable with the size of the depot. This assumption is relaxed in the proposed algorithm; the associated fixed cost is modified each time a new customer is allocated to a depot thus changing the required depot size.     

Local policy networks in the programme Social City—a case in point for new forms of governance in the field of local social work and urban planning1 Lokale Politiknetzwerke im Programm Soziale Stadt—ein Beispielfall für neue Formen von governance im Bereich lokaler Sozialer Arbeit und Stadtplanung

The federal programme Social City represents a concept that is different from traditional urban planning, social work and local economic development as well as planning concepts in various ways. The developmental processes to be set into motion on the level of city districts:

• should make cooperation between various sectors and actors a key issue;

• should encourage them to invest into this cooperation and use the resources to be brought about by their participation and

• furthermore, the participation of various groups of the local population is foreseen.

Building up the respective institutional premises for this kind of networking and participation is part of the programme. Thereby urban planning and policies in social work and social services are to be brought into cooperation. The paper is based on an evaluative study of such local policy networks as they take place in one of the Länder, Hessen. Central results of the analysis will be presented, and suggestions for the programme's further development as a new concept of governance at the local level include some reflections on its potential for legitimising social work in community building.     

The state intervenes in the battle of the sexes: Causal effects of paternity leave

Do family policies influence attitudes and behavior or are they merely reflections of pre-existing attitudes? We consider the implementation of the Norwegian daddy quota, 4 weeks of parental leave reserved for the father, as a natural experiment, and examine the long-run causal effects on attitudes toward gender equality, on conflicts and sharing of household labor, and on support for public childcare. We find that respondents who had their last born child just after the reform report an 11% lower level of conflicts over household division of labor and that they are 50% more likely to equally divide the task of washing clothes than respondents who had their last child just before the reform.     

When what you have is not enough—Acquiring Australian qualifications to overcome non-recognition of overseas skills

Skilled migration is an important strategy in developed economies seeking to address skills shortages and population ageing. Research on the labour market outcomes of skilled migrants tends to focus on employers' devaluation of skills without considering the role of immigration policy in the migration process. Moreover, there is little understanding of whether efforts to meet employer demands for local qualifications improve labour market outcomes. Drawing on a study on skilled migrants sponsored under the State-Specific and Regional Migration Scheme in the regional state of South Australia, we explore the shaping of skills and skills recognition in the migration journey, particularly migrants' strategy of reskilling in response to employer demands for local qualifications. Our logistic regressions on the association between the acquisition of Australian qualifications and labour market outcomes reveal only marginal returns to these efforts. We argue that Australia should consider developing a more coherent skilled migration process to better harness the human capital of skilled migrants.     

The geometry of Gaussian double Markovian distributions

Gaussian double Markovian models consist of covariance matrices constrained by a pair of graphs specifying zeros simultaneously in the matrix and its inverse. We study the semi-algebraic geometry of these models, in particular their dimension, smoothness, and connectedness as well as algebraic and combinatorial properties.     

Sensitivity Analysis Using Risk Measures

In a quantitative model with uncertain inputs, the uncertainty of the output can be summarized by a risk measure. We propose a sensitivity analysis method based on derivatives of the output risk measure, in the direction of model inputs. This produces a global sensitivity measure, explicitly linking sensitivity and uncertainty analyses. We focus on the case of distortion risk measures, defined as weighted averages of output percentiles, and prove a representation of the sensitivity measure that can be evaluated on a Monte Carlo sample, as a weighted average of gradients over the input space. When the analytical model is unknown or hard to work with, nonparametric techniques are used for gradient estimation. This process is demonstrated through the example of a nonlinear insurance loss model. Furthermore, the proposed framework is extended in order to measure sensitivity to constant model parameters, uncertain statistical parameters, and random factors driving dependence between model inputs.     

Variable selection for generalized linear mixed models by L 1-penalized estimation

Generalized linear mixed models are a widely used tool for modeling longitudinal data. However, their use is typically restricted to few covariates, because the presence of many predictors yields unstable estimates. The presented approach to the fitting of generalized linear mixed models includes an L ₁-penalty term that enforces variable selection and shrinkage simultaneously. A gradient ascent algorithm is proposed that allows to maximize the penalized log-likelihood yielding models with reduced complexity. In contrast to common procedures it can be used in high-dimensional settings where a large number of potentially influential explanatory variables is available. The method is investigated in simulation studies and illustrated by use of real data sets.     

Insurance demand and social comparison: An experimental analysis

This paper analyzes whether social comparison can explain the low take-up of disaster insurance usually reported in field studies. We argue that risks in the case of disasters are highly correlated between subjects whereas risks for which high insurance take-up can be observed (e.g. extended warranties or cell phone insurance) are typically idiosyncratic. We set up a simple model with social reference points and show that in the presence of inequality aversion social comparison makes insurance indeed less attractive if risks are correlated. In addition we conducted a simple experiment which confirms these theoretical results. The average willingness to pay for insurance is significantly higher for idiosyncratic than for correlated risks.     

Standardisierungspotentiale lebenszyklusbasierter Modelle des strategischen Kostenmanagements

Tremendous increases in indirect costs can be found in many industries. Consequently, life cycle cost analysis models are getting more important in strategic cost management. However, existing models differ significantly from each other as they have been developed mainly for specific applications. In order to enable a common use of those models, a standardization of these models is required. We examine the potentials of standardizing models for life cycle cost analysis. In a first step, requirements regarding a standard model are derived from literature. As a second step, existing approaches found in literature are compared to the afore derived demands and it is analyzed to what extent they match the standardization requirements. Based on this comparison, we identify and discuss avenues for further research.     

The Dynamics of Research Alliances: Examining the Effect of Alliance Experience and Partner Characteristics on the Speed of Alliance Entry in the Biotech Industry

Few studies have moved beyond the dyadic level of an ongoing alliance and examined factors contributing to the success of entering a series of alliances. In this paper we expect biotechnology firms over time to learn from their alliance experience and to develop general alliance capabilities. Specifically, we expect the speed with which they enter into new research alliances, e.g. their alliance formation rate, to be affected by capabilities built up in prior alliances as well as by characteristics of their partners. We use longitudinal event history data for the complete population of US biotechnology firms for 1973–1999 to test four hypotheses about factors affecting the rate of new alliance formation. Our analysis suggests that the speed of entering research alliances is affected by prior experience of the focal firm, but not by partner characteristics. Our findings provide evidence that biotech firms learn how to learn more effectively from multiple research alliances; however, this effect is generalized and not tied to specific characteristics of the alliance partner.