Estimating the proportion of true null hypotheses using the pattern of observed p-values

Estimating the proportion of true null hypotheses, π₀, has attracted much attention in the recent statistical literature. Besides its apparent relevance for a set of specific scientific hypotheses, an accurate estimate of this parameter is key for many multiple testing procedures. Most existing methods for estimating π₀ in the literature are motivated from the independence assumption of test statistics, which is often not true in reality. Simulations indicate that most existing estimators in the presence of the dependence among test statistics can be poor, mainly due to the increase of variation in these estimators. In this paper, we propose several data-driven methods for estimating π₀ by incorporating the distribution pattern of the observed p-values as a practical approach to address potential dependence among test statistics. Specifically, we use a linear fit to give a data-driven estimate for the proportion of true-null p-values in (λ, 1] over the whole range [0, 1] instead of using the expected proportion at 1?λ. We find that the proposed estimators may substantially decrease the variance of the estimated true null proportion and thus improve the overall performance.     

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.     

Gambling Problems Among Community Cocaine Users

Cocaine use is highly prevalent and a major public health problem. While some studies have reported frequent comorbidity problems among cocaine users, few studies have included evaluation of gambling problems. This study aimed to estimate the prevalence of gambling problems and compare those who were at-risk gamblers with non-problem gamblers in terms of mental health problems, substance use problems, and some risk factors (i.e. family antecedents, erroneous perceptions and coping strategies) among individuals who smoke or inject cocaine. A total of 424 smoked or injected cocaine users recruited through community-based programs in Montreal (Quebec) completed the questionnaire, including the Canadian Pathological Gambling Index, the Composite International Diagnostic Interview, the CAGE, and the Severity Dependence Scale. Of the sample, 18.4 % were considered at-risk gamblers, of whom 7.8 % had problems gambling and 10.6 % were moderate-risk gamblers. The at-risk group was more likely to have experienced a recent phobic disorder and alcohol problems than the non-problem group. A multivariate analysis showed that, compared to those who were non-problem gamblers, the at-risk ones were more likely to have lost a large sum of money when they first started gambling, believed that their luck would turn, and gambled in reaction to painful life events. These results indicate the need to include routines for screening to identify gambling problem among cocaine users.     

Through their eyes: seeing experiences of settlement in photographs taken by refugee background youth in Melbourne,Australia

Although ‘refugees’ are frequently represented in visual media, it is predominantly as the central subject matter and rarely are they positioned as the photographers of their own journeys. In this article, we present photographic images that have been taken by refugee background youth portraying their experiences of the first years of settlement in Australia. We consider how, in our longitudinal research conducted with 120 refugee background youth, visual materials can provide equally important yet different insights in comparison to written or spoken narratives on the experiences of refugee settlement. Through an examination of the photograph’s visual content, we explore the ways in which they portrayed their early experiences of external suburban settlement environments and their depictions of interior spaces and home-making practices. We discuss how these visual insights capture an alternative way of seeing the experiences of becoming at home as the youth become emplaced post-resettlement in Australia. We argue that the photographs taken by these refugee background youth illustrate how visual methods and materials can provide equally important but often overlooked insights into early settlement experiences. Importantly, the photographic images offer a way of portraying the people, places and sentiments that are central to the everyday lives of refugee background youths in ways that oral and written narratives cannot.     

Effects of pushing height on trunk posture and trunk muscle activity when a cart suddenly starts or stops moving

Unexpected sudden (un)loading of the trunk may induce inadequate responses of trunk muscles and uncontrolled trunk motion. These unexpected perturbations may occur in pushing tasks, when the cart suddenly starts moving (unloading) or is blocked by an obstacle (loading). In pushing, handle height affects the user's working posture, which may influence trunk muscle activity and trunk movement in response to the perturbation. Eleven healthy male subjects pushed a 200 kg cart with handles at shoulder and hip height in a start condition (sudden release of brakes) and a stop condition (bumping into an obstacle). Before the perturbation, the baseline of the trunk inclination, internal moment and trunk extensor muscle activity were significantly higher when pushing at hip height than at shoulder height. After the perturbation, the changes in trunk inclination and internal moment were significantly larger when pushing at shoulder height than at hip height in both conditions. The opposite directions of changes in trunk inclination and internal moment suggest that the unexpected perturbations caused uncontrolled trunk motion. Pushing at shoulder height may impose a high risk of low-back injury due to the low trunk stiffness and large involuntary trunk motion occurring after carts suddenly move or stop.     

Children's Postdivorce Residence Arrangements and Parental Experienced Time Pressure

Although the rise in postdivorce joint physical custody has fueled scholarly interest in its impact on children, consequences for parents remain understudied. Because children's residence arrangements determine time and coordination demands associated with child care, this study investigated the relationship between postdivorce residence arrangements and parents' time pressure. Regression analyses on 4,460 formerly married or cohabiting parents in the Netherlands showed that main residence (mother residence, father residence, or joint physical custody) is more strongly related to time pressure than is nonresident parents' visitation frequency. Compared with mother residence, joint physical custody is associated with less time pressure for mothers and slightly greater pressure for fathers, which supports the idea of higher care demands when parents spend more time with their children. The results do not support the role of coordination demands; the extent of interparental contact and the number of transitions the child makes are not related to time pressure.     

The Short French Internet Addiction Test Adapted to Online Sexual Activities: Validation and Links With Online Sexual Preferences and Addiction Symptoms

The goal of this study was to investigate the psychometric properties of a French version of the short Internet Addiction Test adapted to online sexual activities (s-IAT-sex). The French version of the s-IAT-sex was administered to a sample of 401 men. The participants also completed a questionnaire that screened for sexual addiction (PATHOS). The relationships of s-IAT-sex scores with time spent online for online sexual activities (OSAs) and the types of OSAs favored were also considered. Confirmatory analyses supported a two-factor model of s-IAT-sex, corresponding to the factorial structure found in earlier studies that used the short IAT. The first factor regroups loss of control and time management, whereas the second factor regroups craving and social problems. Internal consistency for each factor was evaluated with Cronbach's α coefficient, resulting in .87 for Factor 1, .76 for Factor 2, and .88 for the global scale. Concurrent validity was supported by relationships with symptoms of sexual addiction, types of OSAs practiced, and time spent online for OSAs. The prevalence of sexual addiction (measured by PATHOS) was 28.1% in the current sample of self-selected male OSA users. The French version of the s-IAT-sex presents good psychometric properties and constitutes a useful tool for researchers and practitioners.     

Child Well‐Being: What Does It Mean?

The notion of child well‐being appears in a large number of publications nowadays. Our review of the literature underlines both the oddly pathogenic approach to child well‐being and the scarcity of papers discussing a still poorly defined notion. Through this review, we identified the recourse to a binary language; from there, we derived five theoretical axes that heed the multidimensional and multilevel nature of well‐being, although for each one, a pole is here predominantly developed. We argue in favour of an override of a one‐dimensional, single‐level, unipolar approach to child well‐being and an exploration of its otherwise underdeveloped positive, hedonic, subjective, spiritual and collective dimensions.     

Family 'Decline' and the Subjective Well-being of Adolescents

The goal of the present study was to determine to what extent an adolescent's subjective well-being is affected when changes in family structure reach a breaking point and the child can no longer stay with his family, but must be institutionalized. The participants were one hundred male and female adolescents, 12 to 19 years of age, 50 of which lived in children's homes, but were originally from 50 different families, and 50 of which lived at home with their parents. Two questionnaires were administered: (a) the French adaptation of the Life Satisfaction Scale (Blais et al., 1989) and (b) a questionnaire containing statements related to level of satisfaction in several areas, notably family relationships, body image, work and schooling, and leisure acitivites. The difference between the two groups was considerable, with more than one point separating the mean levels of satisfaction of the two groups (20% of the total length of the scale employed). A structural analysis of the results showed the direct or indirect influence of three factors related to placement in a children's home on life satisfaction: a direct effect of placement in a children's home, an indirect effect passing through the satisfaction with family life, and an indirect effect passing through the personal growth.     

Migrant and asylum-seeker children returned to Kosovo and Albania: predictive factors for social–emotional wellbeing after return

The return of rejected asylum seekers has a high priority on the national agendas of European States. In order to make well-informed asylum decisions involving children, knowledge of how asylum-seeker children fare after their return to their countries of origin is needed. This study aims to gain knowledge about the child-rearing environment and the social–emotional wellbeing of migrant children who have returned to Kosovo and Albania after a stay in a European host country. Based on a sample of 106 returned families, the study investigated the predictive factors for children’s social–emotional wellbeing using regression analyses. The findings show that procedural characteristics and ethnicity predict wellbeing, mediated through the quality of the child-rearing environment. The most vulnerable children did not have a stable resident status in the host country, belonged to a minority ethnic group and were older adolescents. The findings indicate that the wellbeing of returned children is not only dependent on conditions after repatriation, but also on the conditions which the families left in the host country. To enable sustainable return in a child’s best interests, the needs of vulnerable families and children should be thoroughly assessed prior to return, and reintegration support should be tailored to their situation.