Elicitation of multivariate prior distributions: A nonparametric Bayesian approach

In the context of Bayesian statistical analysis, elicitation is the process of formulating a prior density f(·)$f(·)$ about one or more uncertain quantities to represent a person's knowledge and beliefs. Several different methods of eliciting prior distributions for one unknown parameter have been proposed. However, there are relatively few methods for specifying a multivariate prior distribution and most are just applicable to specific classes of problems and/or based on restrictive conditions, such as independence of variables. Besides, many of these procedures require the elicitation of variances and correlations, and sometimes elicitation of hyperparameters which are difficult for experts to specify in practice. Garthwaite et al. (2005) discuss the different methods proposed in the literature and the difficulties of eliciting multivariate prior distributions. We describe a flexible method of eliciting multivariate prior distributions applicable to a wide class of practical problems. Our approach does not assume a parametric form for the unknown prior density f(·)$f(·)$, instead we use nonparametric Bayesian inference, modelling f(·)$f(·)$ by a Gaussian process prior distribution. The expert is then asked to specify certain summaries of his/her distribution, such as the mean, mode, marginal quantiles and a small number of joint probabilities. The analyst receives that information, treating it as a data set D   with which to update his/her prior beliefs to obtain the posterior distribution for f(·)$f(·)$. Theoretical properties of joint and marginal priors are derived and numerical illustrations to demonstrate our approach are given.     

A semiparametric Bayesian approach to extreme value estimation

This paper is concerned with extreme value density estimation. The generalized Pareto distribution (GPD) beyond a given threshold is combined with a nonparametric estimation approach below the threshold. This semiparametric setup is shown to generalize a few existing approaches and enables density estimation over the complete sample space. Estimation is performed via the Bayesian paradigm, which helps identify model components. Estimation of all model parameters, including the threshold and higher quantiles, and prediction for future observations is provided. Simulation studies suggest a few useful guidelines to evaluate the relevance of the proposed procedures. They also provide empirical evidence about the improvement of the proposed methodology over existing approaches. Models are then applied to environmental data sets. The paper is concluded with a few directions for future work.     

Is There a Motherhood Penalty? Decomposing the Family Wage Gap in Colombia

The aim of this paper is to provide an estimation and decomposition of the motherhood wage penalty in Colombia. Our empirical strategy was based on the matching procedure designed by Ñopo (The Review of Economics and Statistics, 90(2), 290–299, 2008a) for the case of gender wage gaps. This is an alternative procedure to the well-known Blinder–Oaxaca decomposition method. Using the cross-sectional data of the Colombian Living Standard Survey, the wage gap was decomposed into four components, according to the characteristics of mothers and non-mothers. Three of the components are explained by differences in observable characteristics of women, while the other is the unexplained part of the gap. We found that mothers earn, on average, 1.73 % less than their counterparts without children and that this gap slightly decreased when the group included older women. It is observed from the results that, once schooling was included as a matching variable, the unexplained part of the gap considerably decreased and became non-significant. Thus, we did not find evidence of wage discrimination against mothers in the Colombian labor market.     

Boundaries are Made to be Crossed: The Magic and Politics of the Long-lasting Amazon/Andes Divide

The construction of Amazonia as a distinct entity, opposed to the Andes, results from processes associated with the expansion of Andean-centered state formations. Analysis of five short texts on the Amazon region, written in colonial and postcolonial Peru by a diversity of social actors, reveals a pervasive rhetoric of alterity whose content varies according to the particular objectives the authors had in mind. In all cases, however, the aim is the same, namely the imposition of boundaries of differentiation as justification for state integration, expressed in the commodification and symbolic consumption of the Amazonian Other. If the politics of boundary making consist in "peripheralizing" and "othering" the Amazon and its people, the magic of boundary making resides in the discursive sleight of hand through which contemporary agents conceal the fact that the Amazon has long ago been incorporated into the nation-state.     

A Re-examination of Defining Moments in Vygotsky's Work and Their Implications for His Continuing Legacy

This article argues for the idea of different moments in Vygotsky's work while highlighting combinations of ideas and concepts that were particularly emphasized in distinct moments of his work. After Vygotsky's death, these moments were not considered a theoretical system in development, either in former Soviet psychology or in Western interpretations of his work. Vygotsky's legacy seems to have been mostly reduced to one concrete focus of his work, mistakenly identified as cultural-historical theory. The overemphasis of selected aspects of Vygotsky's work resulted in an overshadowing of other ideas that have remained relatively “unknown” until fairly recently. In this article, previously underemphasized elements in Vygotsky's psychology, such as emotions, fantasy, imagination, personality, and the generative character of human psyche, are emphasized. A consideration of these elements offers new and refreshing alternatives to Vygotsky's legacy. These previously underemphasized elements are markedly represented in Vygotsky's first and third moments. Furthermore, in the third and final moment of his work, the category of sense opened up a completely new perspective for a systemic and complex approach to understanding the human mind.     

Rainfall Patterns and U.S. Migration from Rural Mexico

In many rural regions of developing countries, natural resource dependency means changes in climate patterns hold tremendous potential to impact livelihoods. When environmentally‐based livelihood options are constrained, migration can become an important adaptive strategy. Using data from the Mexican Migration Project, we model U.S. emigration from rural communities as related to community, household and climate factors. The results suggest that households subjected to very recent drought conditions are less likely to send a U.S. migrant, but in communities with drought two years prior and with strong migration histories, emigration is much more likely. In regions lacking such social networks, rainfall deficits actually reduce migration propensities, perhaps reflecting constraints in the ability to engage in migration as a coping strategy. Policy implications emphasize diversification of rural Mexican livelihoods in the face of contemporary climate change.     

Generalizacion de Una Clasificacion Cognitivo Dimensional de Episodios de Ayuda A Una Muestra EspañOla

En el presente artículo se argumenta que la literatura psicosocial sobre el altruismo carece de un marco teórico que interrelacione distintas formas de ayuda. Se describen las investigaciones de Smithson, Pearce y Amato (1980–83) sobre una taxonomía dimensional de episodios de ayuda en muestras australianas. Intentamos confirmar los resultados de dichas investigaciones y generalizar la taxonomía a una muestra de universitarios españoles. Los análisis multidimensionales reflejan una estructura bidimensional estable a pesar de las diferencias nacionales. Estas dimensiones son: ayuda importante-ayuda no importante y ayuda planificada-ayuda espontánea. Aparecen, además, algunas diferencias culturales en la localización de algunos episodios de ayuda en las dimensiones. Se sugieren algunas hipótesis que pueden explicar estas diferencias.     

The reign of Christ over the nation: The Basque question in the Spanish Republic, 1931–1936

The debate on the Basque Statute during the Spanish Republic (1931–39) became an exceptional political myth in contemporary Basque politics. According to current political narratives of Basque identity, the traditional will to self-government of the Basque people was expressed during those years in a broad demand for autonomy and collective identity. This article outlines the social complexity of the autonomy project, more related to religion than to ethnic conflict. This approach suggests that present concerns with Basque identity narratives undermine the historical parameters operative in the past, disabling our understanding of the history of the Basques.