Tribute to Jean-Yves Jaffray

Tribute to Jean-Yves Jaffray by the French Group of Decision Theory.     

Le faux problème de l'indéfinition de la religion: les origines du ‘problème’ et ses enjeux actuels

When one refuses to participate in shallow debates on the definition of religion, which define in general tactics of declassing the beliefs of others or of under-classing our own beliefs, one recognizes that beyond the emerging patchworked spiritual diversification which emerges in today's advanced industrial societies there is a unified religious dogma. The idea that spirituality will be contradictory to religion does not constitute a pertinent concrete distinction, but occupies a place in this new religious dogma that presents itself as spiritual.     

A comparison of dependence function estimators in multivariate extremes

Various nonparametric and parametric estimators of extremal dependence have been proposed in the literature. Nonparametric methods commonly suffer from the curse of dimensionality and have been mostly implemented in extreme-value studies up to three dimensions, whereas parametric models can tackle higher-dimensional settings. In this paper, we assess, through a vast and systematic simulation study, the performance of classical and recently proposed estimators in multivariate settings. In particular, we first investigate the performance of nonparametric methods and then compare them with classical parametric approaches under symmetric and asymmetric dependence structures within the commonly used logistic family. We also explore two different ways to make nonparametric estimators satisfy the necessary dependence function shape constraints, finding a general improvement in estimator performance either (i) by substituting the estimator with its greatest convex minorant, developing a computational tool to implement this method for dimensions \(D\ge 2\) or (ii) by projecting the estimator onto a subspace of dependence functions satisfying such constraints and taking advantage of Bernstein–Bézier polynomials. Implementing the convex minorant method leads to better estimator performance as the dimensionality increases.     

Initiating a Caregiving Relationship: Pregnancy and Childbirth Factors as Predictors of Maternal Sensitivity

The aim of this study was to investigate the relations between pregnancy and childbirth factors and subsequent quality of maternal interactive behavior in a sample of 116 full‐term infants and their mothers. Mothers reported on the conditions of childbirth when infants were 6–8 months of age, and their interactive behavior was observed during a home visit at 12 months. Results showed that mothers who did not report health problems during pregnancy and who had longer pregnancies, shorter hospital stays, natural deliveries, and infants with greater birthweight were found to be more sensitive during interactions with infants at 12 months. All these relations held after accounting for socio‐economic factors and maternal psychological distress, except for the effect of type of delivery. This pattern of results, however, was almost exclusively due to mothers who already had at least one other child. Very few such relations were found among primiparous mothers.     

Friendships with benefits? Examining the role of friendship in semi-structured interviews within music research

This article explores the ‘methodology of friendship’ and its wider potential within music research. Drawing on two research examples that made use of ‘friendship’ in distinct fashions – one that explores music listening practices in everyday life and the other, music as a site for racialisation – the article discusses how friendship can be incorporated within semi-structured interviews. The case studies act as examples of how to negotiate alterity in music research and how friendship represents a potential for gathering more detailed data. The notion of ‘alterity’, at the core of research relationships is critical to shift the conversation to an informal tone and improve the depth of the discourses gathered from informants. Consequently, this article addresses debates within qualitative (music) sociology by reconsidering friendship as an axis of power and examines the nature of the data gathered in semi-structured interviews through the methodology of friendship.     

The multiplicity of iPod cultures in everyday life: uncovering the performative hybridity of the iconic object

This article looks at the Apple iPod as an iconic and hybrid music object and explores the multiplicity of iPod cultures in everyday life. It reviews the existing literature on the iPod and advances two main paradigms on iPod culture – the individual cognition enabled by the Apple object during private and mobile listening practices or the algorithmic socialization afforded by the use of the Genius recommendation system for example. Tackling these two existing paradigms, I pose the hybridity of the iPod as the basis of its iconicity. Thus, the iPod allows its users to associate its materiality with various sorts of activities in everyday life (individual mobile listening, music sharing, algorithmic connections), and with other material objects (computers, earphones) and media (music social media). As an iconic object that accompanies the various moments of users’ everyday lives, the iPod embodies the new possibilities and directions of music consumption in the digital age of technologies and entangles issues that emerge in contemporary society, such as the increasing blurry separation between individual experiences and social structures.     

Propensity score applied to survival data analysis through proportional hazards models: a Monte Carlo study

Propensity score methods are increasingly used in medical literature to estimate treatment effect using data from observational studies. Despite many papers on propensity score analysis, few have focused on the analysis of survival data. Even within the framework of the popular proportional hazard model, the choice among marginal, stratified or adjusted models remains unclear. A Monte Carlo simulation study was used to compare the performance of several survival models to estimate both marginal and conditional treatment effects. The impact of accounting or not for pairing when analysing propensity‐score‐matched survival data was assessed. In addition, the influence of unmeasured confounders was investigated. After matching on the propensity score, both marginal and conditional treatment effects could be reliably estimated. Ignoring the paired structure of the data led to an increased test size due to an overestimated variance of the treatment effect. Among the various survival models considered, stratified models systematically showed poorer performance. Omitting a covariate in the propensity score model led to a biased estimation of treatment effect, but replacement of the unmeasured confounder by a correlated one allowed a marked decrease in this bias. Our study showed that propensity scores applied to survival data can lead to unbiased estimation of both marginal and conditional treatment effect, when marginal and adjusted Cox models are used. In all cases, it is necessary to account for pairing when analysing propensity‐score‐matched data, using a robust estimator of the variance. Copyright © 2012 John Wiley & Sons, Ltd.     

Comparison of Kernel Density Estimators with Assumption on Number of Modes

A data-driven bandwidth choice for a kernel density estimator called critical bandwidth is investigated. This procedure allows the estimation to have as many modes as assumed for the density to estimate. Both Gaussian and uniform kernels are considered. For the Gaussian kernel, asymptotic results are given. For the uniform kernel, an argument against these properties is mentioned. These theoretical results are illustrated with a simulation study that compares the kernel estimators that rely on critical bandwidth with another one that uses a plug-in method to select its bandwidth. An estimator that consists in estimates of density contour clusters and takes assumptions on number of modes into account is also considered. Finally, the methodology is illustrated using environment monitoring data.     

Contest with attack and defense: does negative campaigning increase or decrease voter turnout?

There are two ways of winning a competition, by increasing one’s own chances of winning or by decreasing those of one’s opponents. I consider a model of contest with attack and defense and propose an application to negative political campaigns, where two candidates choose between disparaging their opponent or valorizing their own image. I provide sufficient conditions for the existence and uniqueness of the symmetric Nash equilibrium of the contest game. Through this model, I then contribute to the controversy concerning the effect of negative campaigning on voter turnout.