Weighted likelihood mixture modeling and model-based clustering

Statistics and Computing - A weighted likelihood approach for robust fitting of a mixture of multivariate Gaussian components is developed in this work. Two approaches have been proposed that are...     

Robust Inference in Generalized Linear Models

Robust inference on the parameters in generalized linear models is performed using the weighted likelihood method. Two cases are considered: a case with replicated observations and a case with a single observation of the dependent variable for each combination of the explanatory variables. The first case is common in the design of experiments, while the second case arises in observational studies. Theoretical and computational results on real datasets are presented and compared with other existing techniques.     

The Promotion of Children's and Adolescents’ Social Participation in Italy and Scotland

This article presents the theoretical framework, methodology and the main results of a comparative research on the promotion of children's social participation in Italy and Scotland, which was based on politicians’, managers’ and practitioners’ representations. Promotion of participation here is considered a form of social intervention in which adults construct and treat children as citizens entitled to be involved in decision‐making processes, due to their competence in self‐expression and making choices. The study revealed a coexistence of different images of childhood and social intervention, as well as some interesting differences and similarities between the two socio‐cultural contexts.     

Wage Discrimination and Female Occupational Intensity

The analysis presented in this paper attempts to shed some light, in the context of the Italian labour market, on wage based gender discrimination effects and on the potential impact of gender occupational distribution on wage determination. The results obtained provide some useful insights for Equal Pay legislation and on the efficacy of Comparable Worth (CW) type policies. The wage equation estimates are broadly in line with results obtained elsewhere in the literature. A discrimination effect of nearly 17|X% results when an exclusively male occupational structure is considered. The gender wage gap showed to decrease as female intensity increases. In terms of the framework used, two competing interpretations have been proposed and their implications discussed. The implication of different policy measures which, in recent years, generated much discussion among scholars and in political arenas have been considered, namely: CW and Affirmative Action (AA) policies. Future research should consider a structural model of discrimination so as to discriminate between competing models and policy options.     

The Outward Projection of Italian Firms: Facts and Figures on Foreign Affiliates

In the last two decades or so, globalisation has prompted a great deal of attention in the study of the international organisation of production, with in-depth industry studies on its welfare effects, both for firms and for workers. Outcomes did not prove a unique direction of effects, although the heterogeneous firms?? approach emphasised the intra-industry reallocation through intra-sectoral international competition. Thus, differences in the inner structure of companies filled the gap on the micro-level analysis that featured the study of international trade for several decades, although there is still the need to understand the effects of internationalisation on local systems of production and link such results to the consolidated meso-level of analysis of trade flows. Thanks to the microdata provided by the Italian Statistical Office (ISTAT), we are able to access information on the presence of Italian firms abroad, distinguished by geographical area of origin, destination and industry and check for their influence on affiliates?? structure and performance through appropriate indicators.     

Union Density and Relative Wages: What is the Relationship?

ABSTRACT: This paper examines the impact of union density on relative wages under decentralised bargaining settings. Whilst, traditionally, empirical studies have focused on the impact of union status on wages (either at the individual or at the plant level), here it is argued that local trade union density can have an independent (positive) effect on wages. This occurs through the threat of collective action and the ability of the union to impose costs onto employers. First, a Nash bargaining model is presented under efficient-bargaining settings, and a wage-membership equation is derived. Wages are shown to be an increasing and convex function of union membership. Second, an empirical specification of the wage-membership equation, suitable for estimation, is obtained and fitted to establishment-level data for the Italian metal-mechanical engineering industry. A positive monotonic relationship between wages and union density is detected. Furthermore, wages are shown to be increasing with union density even where no formal local bargaining agreement is in force, thus suggesting that “union-threat” effects might be relevant.     

New ways of specifying data edits

Summary.   Data editing is the process by which data that are collected in some way (a statistical survey for example) are examined for errors and corrected with the help of software. Edits, the logical conditions that should be satisfied by the data, are specified by subject-matter experts with a procedure which could be tedious and could lead to mistakes with practical implications. To render the process of edit specification more efficient we provide a new step—the definition of the so-called abstract data model of a survey—which describes the structure of the phenomenon that is studied in a survey. The existence of this model enables experts to identify all combinations of variables which should be checked by edits and to avoid the definition of conflicting edits. Furthermore, we introduce an automatic data validation strategy—TREEVAL—that consists of fast tree growing to derive automatically the functional form of edits and of a statistical criterion to clean the incoming data. The TREEVAL strategy is cast within a total quality management framework. The application of the methodologies proposed is demonstrated with the help of a real life application.     

Understanding the Processes Underlying Inter‐firm Collaboration: Mutual Forbearance and the Principle of Congruity

This paper makes a theoretical innovation by integrating two key principles – mutual forbearance and the principle of congruity – into one general process model. It examines the micro‐mechanisms underlying the formation of a mutual‐forbearance agreement and explicates the role of time and of individual actions. We further understanding of the process of cooperation building by drawing a parallel between early stages of the formation process of mutual forbearance and cooperation, and argue that mutual forbearance may, under certain conditions, lead to long‐term cooperation or, if mismanaged, completely smother any chances of it. A prospective agreement may be put at risk when potential contributions are evaluated differently by each party and no action to mitigate the consequences is taken; even more so in a mutual‐forbearance context when the parties can only observe their counterparts’ actions through the market. Our model takes into account the micro‐mechanisms associated with the time between the actions of one entity/individual (e.g. the top manager) and the reaction of another entity/individual, the boundary conditions of the background to those actions and the alternative actions available during this time. Propositions for further exploration and implications are drawn.     

Social Policy for Poverty Reduction in Lower-income Countries in Latin America: Lessons and Challenges

This article provides a comparative study of income transfer programmes recently introduced in lower-income countries in Central and South America, aimed at raising human development and consumption among groups in extreme poverty. The successful introduction of these programmes is challenging in these countries due to their high incidence of poverty, low delivery capacity and poor service infrastructure. The article discusses the design, implementation and impact of these programmes, as well as their institutionalization and dynamics. It concludes that these programmes can be effective in reducing persistent intergenerational poverty, but that their sustainability is undermined by weak institutionalization.