Stability of feature selection in classification issues for high-dimensional correlated data

Handling dependence or not in feature selection is still an open question in supervised classification issues where the number of covariates exceeds the number of observations. Some recent papers surprisingly show the superiority of naive Bayes approaches based on an obviously erroneous assumption of independence, whereas others recommend to infer on the dependence structure in order to decorrelate the selection statistics. In the classical linear discriminant analysis (LDA) framework, the present paper first highlights the impact of dependence in terms of instability of feature selection. A second objective is to revisit the above issue using a flexible factor modeling for the covariance. This framework introduces latent components of dependence, conditionally on which a new Bayes consistency is defined. A procedure is then proposed for the joint estimation of the expectation and variance parameters of the model. The present method is compared to recent regularized diagonal discriminant analysis approaches, assuming independence among features, and regularized LDA procedures, both in terms of classification performance and stability of feature selection. The proposed method is implemented in the R package FADA, freely available from the R repository CRAN.     

Incidence des envois de fonds: une analyse à partir du cas de saisonniers mexicains employés au Canada

À partir d'une enquête menée auprès de saisonniers mexicains au Canada, les auteurs construisent un modèle à équations simultanées reposant sur la méthode des triples moindres carrés. Ils montrent que les envois de fonds ont un effet positif sur l'investissement agricole, et donc sur le revenu agricole au Mexique. Cet effet s'étend au revenu non agricole du fait d'une diversification des activités et des investissements des migrants. Ces résultats confirment la thèse de la nouvelle économie de la migration de travail: les envois de fonds contribuent effectivement au développement économique en donnant aux petits exploitants les liquidités qui leur manquent pour investir.     

Promising Practices of Nonprofit Organizations to Respond to the Challenges Faced in Countering the Mistreatment of Older Adults

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - This article discusses promising practices used by employees and volunteers in nonprofit organizations (NPOs) in...     

Trajectories of team and individual sports participation in childhood and links with internalizing problems

The purpose of this 5-year longitudinal study is to identify trajectories of team and individual sports participation in childhood, and to compare these trajectories on different types of internalizing problems. Parents reported their children's annual sports participation from the ages of 6–10 (n = 785) and teachers reported internalizing problems (depression, anxiety, social withdrawal) at the beginning and at the end of this period. The study used latent class growth analyses to identify two trajectories of team sports and two trajectories of individual sports participation were identified: (1) high participation, and (2) low participation. Considering baseline level of internalizing problems and gender, children in the high participation team sports trajectory show significantly fewer depression, anxiety, and social withdrawal behaviors at age 10 than those in the low participation team sports trajectory. No differences between individual sports trajectories were observed. Comparison with joint trajectory groups partially confirmed these results but also showed that sustained participation in multiple individual sports could also be linked to decreased anxiety. Our findings suggest that participation in team sports should be encouraged to promote certain aspects of children's mental health.     

European System of Accounts: The French Case

The 1995 European System of Accounts (1995 ESA), an adapted version of the United Nations System of National Accounts (1993 SNA), will be applied in most European countries. This research note shows that the empirical knowledge of the nonprofit sector is not improved in this change. We first review the treatment of the nonprofit organizations in 1968 SNA, and then discuss the 1993 SNA and 1995 ESA approaches, which do not clear up many conceptual difficulties. The classification of the private nonprofit institutions serving households by the French statistical office is also presented and criticized. A way forward through the use of a satellite account system is proposed.     

The Role of Rhetoric in a Dialogical Approach to Thinking

The central idea of the paper is that human thinking consists in a movement through which a person socially interacts with herself. Consequently, thinking does not offer the experience of a private refuge in the intimacy of the individual thinker's self‐knowing, but a field where multiple points of view interact by contesting, distancing, approaching, agreeing or disagreeing, one to another. Classical ( Isocrates, 1929 /1968) and contemporary (Billig, 1987) rhetorical approaches to thinking stress that both “inner” and “social” discourse are addressed to someone else, are determined by the anticipation of this audience, and both are interested in persuading it. In doing so, the discursive, rhetoric, and dialogic aspects of thinking become tied to argumentation. The paper tries to show, following the dialogical notion of discourse of Bakhtin (1986) and Volo?inov (1929/1986) that, since every act of thinking consists in the raising of a point of view addressing another one and oriented by a particular interest, every stream of thought involves a rhetorical activity. A distinction between rhetoric and argumentation is proposed. On this basis, the rhetorical nature of thinking is discussed beyond argumentative discourse. Overall, this discussion contributes to a rhetorical approach to dialogism.     

BRAIN DRAIN IN GLOBALIZATION: A GENERAL EQUILIBRIUM ANALYSIS FROM THE SENDING COUNTRIES' PERSPECTIVE

According to the economic literature, high‐skilled emigration may either harm or benefit developing economies. Recent research highlighted several positive and negative channels through which the brain drain operates. This paper aims at evaluating the relative magnitudes of various brain drain channels and quantifying their global impact on migrants' sending countries. For this purpose, we develop a 10‐region general equilibrium model of the world economy characterized by overlapping‐generations dynamics. Our findings suggest that the short‐run impact of brain drain on resident human capital is extremely crucial, as it affects not only the number of high‐skilled workers available to domestic production, but also the sending economy's capacity to innovate/adopt modern technologies. This latter effect is particularly important in globalization, where capital investments are made in places with high production efficiencies. Hence, despite positive feedback effects, those countries facing prevalent high‐skilled emigration are the most candid victims to brain drain. (JEL F22, J24, O57)