Bayesian kernel projections for classification of high dimensional data

A Bayesian multi-category kernel classification method is proposed. The algorithm performs the classification of the projections of the data to the principal axes of the feature space. The advantage of this approach is that the regression coefficients are identifiable and sparse, leading to large computational savings and improved classification performance. The degree of sparsity is regulated in a novel framework based on Bayesian decision theory. The Gibbs sampler is implemented to find the posterior distributions of the parameters, thus probability distributions of prediction can be obtained for new data points, which gives a more complete picture of classification. The algorithm is aimed at high dimensional data sets where the dimension of measurements exceeds the number of observations. The applications considered in this paper are microarray, image processing and near-infrared spectroscopy data.     

The potential for bias in reporting of industry-sponsored clinical trials

Concerns about potentially misleading reporting of pharmaceutical industry research have surfaced many times. The potential for duality (and thereby conflict) of interest is only too clear when you consider the sums of money required for the discovery, development and commercialization of new medicines. As the ability of major, mid-size and small pharmaceutical companies to innovate has waned, as evidenced by the seemingly relentless decline in the numbers of new medicines approved by Food and Drug Administration and European Medicines Agency year-on-year, not only has the cost per new approved medicine risen: so too has the public and media concern about the extent to which the pharmaceutical industry is open and honest about the efficacy, safety and quality of the drugs we manufacture and sell. In 2005 an Editorial in Journal of the American Medical Association made clear that, so great was their concern about misleading reporting of industry-sponsored studies, henceforth no article would be published that was not also guaranteed by independent statistical analysis. We examine the precursors to this Editorial, as well as its immediate and lasting effects for statisticians, for the manner in which statistical analysis is carried out, and for the industry more generally.     

SCHOOL RACIAL COMPOSITION AND BIRACIAL ADOLESCENTS' SCHOOL ATTACHMENT

Despite extensive research on multiracial youth in recent years, to date, no empirical studies have analyzed how racial context may affect biracial adolescents' sense of belonging in a social institution beyond families. In this study, we examine how the racial makeup of the student body affects self-identified biracial adolescents' school attachment. Using data from the National Longitudinal Study of Adolescent Health, we find that the proportions of white or black students in school significantly affect the school attachment of Hispanic/black, Asian/black, and American Indian/black biracial adolescents, but school racial composition in general has little influence on biracial adolescents with a partial-white identification (i.e., black/white, Hispanic/white, Asian/white, and American Indian/white). Our analyses also show that on average, students of most biracial groups display lower school attachment than their corresponding monoracial groups, but the differences from the monoracial groups with the lower school attachment are generally small. We discuss the implications of our findings for biracial adolescents' perceived racial boundaries and contemporary American race relations.     

Striving to be ‘good’ mothers: abused women's experiences of mothering

So far, limited work has focused on women's experiences of mothering in the context of domestic violence. This article presents the findings of a study that investigated women's experiences of mothering in the context of domestic violence and, while it accounts for the difficulties and challenges these women face, it emphasises their desire to be ‘good’ mothers and the strategies they develop in order to achieve ‘good’ mothering. The findings demonstrate that abused women typically strive to be ‘good’ mothers, which requires them to put their children first and to protect and care for them. The recognition of these strategies provides ground to question current professional practices and to develop interventions that will best support women and children living with domestic violence. Copyright © 2010 John Wiley & Sons, Ltd.     

Social-professional status, identity, social participation and media utilization. Analysis of a complex dynamics

This article examines the link between the domain and level of occupation, on the one hand, and use of media, including internet, on the other. It adds to this investigation an analysis of identity in its relation to media use and accessibility. It challenges the hypothesis of a strong correlation between level of occupation and use and accessibility to media. It reveals complex phenomena of social homogenization and differentiation. Data is extracted from a sample of workers who completed a questionnaire which focused on use of media.     

Computationally simple estimation and improved efficiency for special cases of double truncation

Doubly truncated survival data arise when event times are observed only if they occur within subject specific intervals of times. Existing iterative estimation procedures for doubly truncated data are computationally intensive (Turnbull 38:290–295, 1976; Efron and Petrosian 94:824–825, 1999; Shen 62:835–853, 2010a). These procedures assume that the event time is independent of the truncation times, in the sample space that conforms to their requisite ordering. This type of independence is referred to as quasi-independence. In this paper we identify and consider two special cases of quasi-independence: complete quasi-independence and complete truncation dependence. For the case of complete quasi-independence, we derive the nonparametric maximum likelihood estimator in closed-form. For the case of complete truncation dependence, we derive a closed-form nonparametric estimator that requires some external information, and a semi-parametric maximum likelihood estimator that achieves improved efficiency relative to the standard nonparametric maximum likelihood estimator, in the absence of external information. We demonstrate the consistency and potentially improved efficiency of the estimators in simulation studies, and illustrate their use in application to studies of AIDS incubation and Parkinson’s disease age of onset.     

Women's abuse of their children in the context on domestic violence: reflection from women's accounts

This paper draws upon the findings of a study that looked at women's experiences of mothering in the context of co-occurrence of domestic violence and child abuse, and considers the issue of women's violence towards children – while acknowledging the fact that men are the main perpetrators of violence towards women and children in these families. The paper first explores the relationship between women's victimization and women's violence, and suggests that women's abuse of their children can be seen as a consequence of their own experiences of domestic violence. The findings nonetheless suggest that abused women have agency, and therefore have responsibilities when they chose to use violence towards their children. The paper also considers the feelings of guilt and blame that tend to arise in these circumstances. Implications for research, policy and practice are identified.     

Rising food security concerns among New Zealand adolescents and association with health and wellbeing

The current paper explores recent changes in food insecurity among adolescents and determine if food security concerns are associated with poorer wellbeing. Data were collected as part of two nationally representative surveys of the health and wellbeing of high-school students in New Zealand in 2007 and 2012. In 2012, 11% of young people reported food security concerns often or always, with 33% reporting food security concerns occasionally/sometimes. The prevalence of food security concerns at both frequencies increased significantly from 2007 (8% and 28%, respectively). Young people with food security concerns were more likely to report poor indicators of health and wellbeing, including truancy, poor general health, mental health concerns and obesity. Our findings highlight the growing concerns of food insecurity reported by adolescents in New Zealand. Interventions that address food security for families may provide a tangible means of promoting the healthy development of children and young people.     

A generalized multivariate beta distribution: control charting when the measurements are from an exponential distribution

In Statistical Process Control (SPC) there exists a need to model the run-length distribution of a Q-chart that monitors the process mean when measurements are from an exponential distribution with an unknown parameter. To develop exact expressions for the probabilities of run-lengths the joint distribution of the charting statistics is needed. This gives rise to a new distribution that can be regarded as a generalized multivariate beta distribution. An overview of the problem statement as identified in the field of SPC is given and the newly developed generalized multivariate beta distribution is proposed. Statistical properties of this distribution are studied and the effect of the parameters of this generalized multivariate beta distribution on the correlation between two variables is also discussed.