Bayesian and Robust Bayesian analysis under a general class of balanced loss functions

For estimating an unknown parameter θ, we introduce and motivate the use of balanced loss functions of the form L_{r, w, d0}(q, d)=wr(d₀, d)+ (1-w) r(q, d){L_{\rho, \omega, \delta_0}(\theta, \delta)=\omega \rho(\delta_0, \delta)+ (1-\omega) \rho(\theta, \delta)}, as well as the weighted version q(q) L_{r, w, d0}(q, d){q(\theta) L_{\rho, \omega, \delta_0}(\theta, \delta)}, where ρ(θ, δ) is an arbitrary loss function, δ ₀ is a chosen a priori “target” estimator of q, w ? [0,1){\theta, \omega \in[0,1)}, and q(·) is a positive weight function. we develop Bayesian estimators under L_{r, w, d0}{L_{\rho, \omega, \delta_0}} with ω > 0 by relating such estimators to Bayesian solutions under L_{r, w, d0}{L_{\rho, \omega, \delta_0}} with ω = 0. Illustrations are given for various choices of ρ, such as absolute value, entropy, linex, and squared error type losses. Finally, under various robust Bayesian analysis criteria including posterior regret gamma-minimaxity, conditional gamma-minimaxity, and most stable, we establish explicit connections between optimal actions derived under balanced and unbalanced losses.     

Impact of physical activity and sedentary behaviour on fall risks in older people: a systematic review and meta-analysis of observational studies

The objective of this work was to summarise and evaluate the evidence showing that physical activity is a protector factor as regards falls in older people. Relevant studies were identified through a systematic search in the MEDLINE and Cochrane Library, under the keywords of accidental fall/numerical data and risk factors, and with the bibliographies of retrieved papers. The combined odds ratio (OR) [95% confidence interval] for physical activity was 0.75 [0.64, 0.88] with moderate heterogeneity (I ²?=?33%). For fall injury, it was 0.59 [0.47, 0.74] and, for falls in general, it rose to 0.94 [0.76, 1.17] with nil heterogeneity. The combined OR for sedentary factors was 1.14 [1.10, 1.82] with moderate heterogeneity (I ²?=?36%). Regular physical activity in daily life yields significant reduction in falls in older people, especially falls with injuries.     

On An Intriguing Distributional Identity

For a continuous random variable X with support equal to (a, b), with c.d.f. F, and g: Ω₁ → Ω₂ a continuous, strictly increasing function, such that Ω₁∩Ω₂?(a, b), but otherwise arbitrary, we establish that the random variables F(X) ? F(g(X)) and F(g^{? 1}(X)) ? F(X) have the same distribution. Further developments, accompanied by illustrations and observations, address as well the equidistribution identity U ? ψ(U) = ^dψ^{? 1}(U) ? U for U ～ U(0, 1), where ψ is a continuous, strictly increasing and onto function, but otherwise arbitrary. Finally, we expand on applications with connections to variance reduction techniques, the discrepancy between distributions, and a risk identity in predictive density estimation.     

Corporate social responsibility and governance

Journal of Management and Governance -     

Interplay between Friends' Aggression and Friendship Quality in the Development of Child Aggression during the Early School Years

The aim of this study was to investigate the unique and combined role of friendship quality and friends' aggression in regard to the persistence of young children's physical aggression from kindergarten to grade 2. The sample included 1555 children (808 girls) assessed annually using teacher ratings. Two theoretical perspectives (i.e., the social learning and the social bonding perspectives) served as frameworks to guide the analyses and interpret the results. In line with the social learning perspective, friends' aggression was related to a significant increase in children's physical aggression. However, in line with the social bonding perspective, good friendship quality played both a compensatory and a protective role, by, respectively, reducing children's initial level of physical aggression and by mitigating, albeit marginally, the associations between friends' and children's physical aggression. These results suggest that fostering a positive relationship between friends in the early school years may decrease physical aggression even if the friends are aggressive.     

Conditional VAR and Expected Shortfall: A New Functional Approach

We estimate two well-known risk measures, the value-at-risk (VAR) and the expected shortfall, conditionally to a functional variable (i.e., a random variable valued in some semi(pseudo)-metric space). We use nonparametric kernel estimation for constructing estimators of these quantities, under general dependence conditions. Theoretical properties are stated whereas practical aspects are illustrated on simulated data: nonlinear functional and GARCH(1,1) models. Some ideas on bandwidth selection using bootstrap are introduced. Finally, an empirical example is given through data of the S&P 500 time series.     

Overcoming “Crisis”: Mobility Capabilities and “stretching” a Migrant Identity among Young Irish in London and Return Migrants

We bring into dialogue the migrant identities of young Irish immigrants in the UK and young returnees in Ireland. We draw on 38 in-depth interviews (20 in the UK and 18 in Ireland), aged 20–37 at the time of interview, carried out in 2015–16. We argue that “stretching” identities – critical and reflective capabilities to interpret long histories of emigration and the neglected economic dimension – need to be incorporated into conceptualizing “crisis” migrants. Participants draw on networks globally, they choose migration as a temporary “stop-over” abroad, but they also rework historical Irish migrant identities in a novel way. Becoming an Irish migrant or a returnee today is enacted as a historically grounded capability of mobility. However, structural economic constraints in the Irish labour market need to be seriously considered in understanding return aspirations and realities. These findings generate relevant policy ideas in terms of relations between “crisis” migrants and the state.     

Long‐Term Contribution of Immigration to Population Renewal in Canada: A Simulation

We analyze the direct and indirect demographic contribution of immigration to the foreign‐origin composition of the Canadian population according to various projection scenarios over a century, from 2006 to 2106. More specifically, we use Statistics Canada's Demosim microsimulation model to assess the long‐term sensitivity to immigration levels and the frequency of mixed unions of the share of immigrants in Canada and of persons who have at least one ancestor who arrived after 2006. The results of the simulations show that the population renewal process through immigration happens at a fast pace in a high immigration and low fertility country such as Canada. Under the scenarios developed, immigrants who entered after 2006 and their descendants could form the majority of the population by 2058 at the earliest and by 2079 at the latest and could represent between 62 percent and 88 percent in 2106. They also show that mixed unions are a key element of the speed at which the changes are likely to occur in the long run.     

Co-morbidity Between Gambling Problems and Depressive Symptoms: A Longitudinal Perspective of Risk and Protective Factors

In both adolescents and adults, gambling problems and depressive symptoms co-occur and share some common risk factors (e.g., impulsivity and socio-family risk). However, little is known about (1) the developmental course of the co-morbidity of these problems; (2) variables that may moderate the effect of these common risk factors on gambling problems and depressive symptoms. Of specific interest could be individuals’ social relationships with significant others such as parents and friends, because research shows that they moderate the effect of other risk factors on gambling problems and depressive symptoms. The goals of this study were to: (a) identify developmental pathways for gambling problems and depressive symptoms, with a focus on co-morbidity; (b) assess the moderating effect of relationship quality with parents and friends on the link between common risk factors and the trajectories of gambling problems and depressive symptoms. Study participants were 878 males. Predictors were assessed during childhood and adolescence and gambling problems and depressive symptoms were assessed in late adolescence and young adulthood. Latent class analysis revealed four distinct joint trajectories of gambling problems and depressive symptoms. Subsequent logistic regression revealed that impulsivity predicted membership in all pathogenic trajectories, and quality of the relationship with parents predicted membership in depressogenic trajectories. In addition, we found that the membership in the comorbid trajectory can be predicted by an interaction between friendship quality and socio-family risk.