Marginal models for the association structure of hierarchical binary responses

Clustered binary responses are often found in ecological studies. Data analysis may include modeling the marginal probability response. However, when the association is the main scientific focus, modeling the correlation structure between pairs of responses is the key part of the analysis. Second-order generalized estimating equations (GEE) are established in the literature. Some of them are more efficient in computational terms, especially facing large clusters. Alternating logistic regression (ALR) and orthogonalized residual (ORTH) GEE methods are presented and compared in this paper. Simulation results show a slightly superiority of ALR over ORTH. Marginal probabilities and odds ratios are also estimated and compared in a real ecological study involving a three-level hierarchical clustering. ALR and ORTH models are useful for modeling complex association structure with large cluster sizes.     

An approximation to the convolution of gamma distributions

In general, the exact distribution of a convolution of independent gamma random variables is quite complicated and does not admit a closed form. Of all the distributions proposed, the gamma-series representation of Moschopoulos (1985 Moschopoulos, P. G. (1985). The distribution of the sum of independent gamma random variables. Annals of the Institute of Statistical Mathematics 37Part A:541–544. [Google Scholar]) is relatively simple to implement but for particular combinations of scale and/or shape parameters the computation of the weights of the series can result in complications with too much time consuming to allow a large-scale application. Recently, a compact random parameter representation of the convolution has been proposed by Vellaisamy and Upadhye (2009 Vellaisamy, P., Upadhye, N. S. (2009). On the sums of compound negative binomial and gamma random variables. Journal of Applied Probability 46:272–283.[Crossref], [Web of Science ®] , [Google Scholar]) and it allows to give an exact interpretation to the weights of the series. They describe an infinite discrete probability distribution. This result suggested to approximate Moschopoulos’s expression looking for an approximating theoretical discrete distribution for the weights of the series. More precisely, we propose a general negative binomial distribution. The result is an “excellent” approximation, fast and simple to implement for any parameter combination.     

A gradient-based deletion diagnostic measure for generalized linear mixed models

A gradient-statistic-based diagnostic measure is developed in the context of the generalized linear mixed models. Its performance is assessed by some real examples and simulation studies, in terms of ability in detecting influential data structures and of concordance with the most used influence measures.     

Cultural Attunement in Therapy With Mexican‐Heritage Couples: A Grounded Theory Analysis of Client and Therapist Experience

There is a need for culturally attuned approaches for couple therapy with Mexican/Mexican‐Americans. This qualitative grounded theory study utilized interviews with 11 client couples of Mexican heritage and 14 marital and family therapists to shed light on how Latino and non‐Latino therapists co‐construct positive experiences of cultural attunement with Mexican and Mexican‐American couple clients. Analysis identified a model of cultural connection through personal engagement with four interrelated phases: (a) mutual invitation, (b) shared engagement, (c) expanding personal connection, and (d) creating cultural connections. Clients in this study valued professionalism and expertise of the therapist, but felt attuned to and respected when therapists demonstrated humility, shared personal stories and emotion, and engaged in a collaborative process.     

Insolvency Proceedings and Workers’Rights: the Italian Case

ABSTRACT: In this paper the author analyses different types of insolvency proceedings in the context of the Italian legal system, focusing on the possible effects of bankruptcy law on employment relationships. The concept of‘privileged workers’claims is discussed, taking into account their rank of preference as stated by statutory law and according to the interpretations offered by jurisprudence. One section is expressly devoted to the recent legislation providing a Guarantee Fund for severance allowance claims in case of insolvency, but also in the event of mere nonpayment by the employer. After having covered the concept of 'super-privileged claims', the paper discusses more widely possible forms of protecting workers in a situation of company crisis and links between social legislation on the one hand, and bankruptcy law on the other. Finally, the author emphasizes the more effective protection now offered by the Italian legal system to workers’claims, although the trade unions have considerable difficulty in keeping the workforce united when insolvency proceedings are opened.     

A Comparative Study of Segregation Patterns in Belgium,Denmark, the Netherlands and Sweden: Neighbourhood Concentration and Representation of Non-European Migrants

In this paper, we use geo-coded, individual-level register data on four European countries to compute comparative measures of segregation that are independent of existing geographical sub-divisions. The focus is on non-European migrants, for whom aggregates of egocentric neighbourhoods (with different population counts) are used to assess small-scale, medium-scale, and large-scale segregation patterns. At the smallest scale level, corresponding to neighbourhoods with 200 persons, patterns of over- and under-representation are strikingly similar. At larger-scale levels, Belgium stands out as having relatively strong over- and under-representation. More than 55% of the Belgian population lives in large-scale neighbourhoods with moderate under- or over-representation of non-European migrants. In the other countries, the corresponding figures are between 30 and 40%. Possible explanations for the variation across countries are differences in housing policies and refugee placement policies. Sweden has the largest and Denmark the smallest non-European migrant population, in relative terms. Thus, in both migrant-dense and native-born-dense areas, Swedish neighbourhoods have a higher concentration and Denmark a lower concentration of non-European migrants than the other countries. For large-scale, migrant-dense neighbourhoods, however, levels of concentration are similar in Belgium, the Netherlands, and Sweden. Thus, to the extent that such concentrations contribute to spatial inequalities, these countries are facing similar policy challenges.     

The determinants of transnational entrepreneurship and transnational ties’ dynamics among immigrant entrepreneurs in ICT sector in Italy

This article contributes to the rapidly growing literature on transnational immigrant entrepreneurship by analyzing the determinants of transnational entrepreneurial engagement among immigrants in the ICT sector in Italy. We investigate which factors influence the rise or decline of transnational entrepreneurial involvement with a home country. Our results indicate that longer residence in Italy is associated with smaller propensity to become a transnational entrepreneur. Moreover, we find that the type of transnational ties and the network size have a substantial impact on the dynamics of transnational entrepreneurial engagement.     

Neural networks in production planning and control

The purpose of this paper is to present a selection of the most significant ANN (artificial neural network) applications used to solve PPC (production planning and control) problems. Therefore, the paper itself is a reasoned classification rather than a simple survey. The PPC domain is divided into various areas, and for each area one or more examples of ANNs are discussed, together with the benefits and drawbacks of their application to that particular area. Finally, two case studies developed by the authors are reported and discussed to analyse the main implementation problems to be considered when using ANNs.