An Improved Method on Wilcoxon Rank Sum Test for Gene Selection from Microarray Experiments

Selecting a small subset out of the thousands of genes in microarray data is important for accurate classification of phenotypes. In this paper, we propose a flexible rank-based nonparametric procedure for gene selection from microarray data. In the method we propose a statistic for testing whether area under receiver operating characteristic curve (AUC) for each gene is equal to 0.5 allowing different variance for each gene. The contribution to this “single gene” statistic is the studentization of the empirical AUC, which takes into account the variances associated with each gene in the experiment. Delong et al. proposed a nonparametric procedure for calculating a consistent variance estimator of the AUC. We use their variance estimation technique to get a test statistic, and we focus on the primary step in the gene selection process, namely, the ranking of genes with respect to a statistical measure of differential expression. Two real datasets are analyzed to illustrate the methods and a simulation study is carried out to assess the relative performance of different statistical gene ranking measures. The work includes how to use the variance information to produce a list of significant targets and assess differential gene expressions under two conditions. The proposed method does not involve complicated formulas and does not require advanced programming skills. We conclude that the proposed methods offer useful analytical tools for identifying differentially expressed genes for further biological and clinical analysis.     

Some restrictions on the use of corner method hypothesis tests

Beguin et al (1980) introduced the Corner Method as a tool for identifying the order (p,q) of an ARMA proc.ess. In addition they derived approximate hypothesis tests,based on asymptotic theory, to aid in the identification. We show that there are restrictions implicit in the use of these tests which, if violated,could yield spurious results.     

The Effects of a Healthy Families Home Visitation Program on Rapid and Teen Repeat Births

The prevention of Rapid Repeat Births (RRBs) and Teen Repeat Births (TRBs) is an important indicator of the effectiveness of home visitation programs that serve mothers who are at-risk for child maltreatment. This study examined the effects on RRBs and TRBs of a rural/small town home visitation program based on the Healthy Families America (HFA) model. The participants in this study were referred between 1999 and 2007 and included a Treatment Group of 140 at-risk mothers who met minimum engagement criteria and a Comparison Group of 241 at-risk mothers who were referred for services but not enrolled due to limits on program capacity. In addition, county-wide TRB data was used as the basis for a static group comparison. With regard to RRBs, the rates for the Treatment (18%) and Comparison (30%) groups were compared using a Chi-Square test of homogeneity. The null hypothesis that there would be no difference between the rates for the two groups was rejected at the .05 level. Similarly, with regard to TRBs, the null hypothesis that there would be no difference between the rates for the Treatment (9%) and Comparison (27%) groups was rejected at that .01 level. Furthermore, using a Chi-Square test of independence, this investigation tested the null hypothesis that the rates for the two groups would not differ from the county-wide rate (24%). This hypothesis was also rejected at the .01 level. Overall, these results of this inquiry support the conclusion that participants in a rigorously implemented HFA program show significantly lower rates of RRB and TRB when compared to a comparable group of at-risk nonparticipants. They also appear to have a significantly lower incidence of TRB than teen mothers in the general population.     

Distribution-free partially sequential piacment procedures

The concept of a partially sequential hypothesis test was introduced by Wolfe (1977a), an{associated procedures were developed for both parametric and nonparametric assumptions. In this paper we consider distribution-free extensions of those indicator tests, based on the placements of the sequentially obtained observations among the previously collected fixed size sample. Exact and asymptotic, as the fixed sample size in¬creases to infinity, properties of these sequential placements procedures are obtained, including statements about the power and expected number of sequentially obtained observations. The results of a Monte Carlo study are used to differentiate be¬tween various placement scoring schemes.     

A circular test of association between a point process and a continuous time series

A test of association between a point process and a continuous time series is proposed. The test is exact for a general class of point processes, including Poisson processes. Simulation results for a Poisson point process are reported.     

The Biosociology of Solidarity

For well over a century, sociologists have directed considerable attention to understanding and explaining the processes that produce social solidarity – the feeling of interpersonal connectedness that binds members of society together. Despite the centrality of solidarity to sociological thought, many sociologists remain unaware of the biosocial processes and mechanisms that create and sustain it. We espouse a biosociological viewpoint, which illuminates solidarity as a complex and fascinating interplay between biological and social elements. In this paper we discuss three important advances within the field of neuroscience that point to exciting new avenues of research for sociologists: (i) the discovery of mirror neurons, (ii) developments in the understanding of brain plasticity, and (iii) increased appreciation of the role of non‐conscious processes in social interaction. Additionally, we discuss ongoing basic and applied research to demonstrate how sociologists can capitalize on recent scientific developments to advance their own research agendas. VIDEO ABSTRACT ‐ http://www.youtube.com/watch?v=Is9de_ajheM&hd=1     

Using feminist ‘reflexive practice’ to explore stress and well-being of local researchers in South Sudan

ABSTRACT

This article discusses using feminist methods of reflexive practice to support and learn about the well-being of researchers working on gender-based violence research in South Sudan. In particular, we focus on the experiences of South Sudanese researchers undertaking this research in their own country. We share key findings and offer personal reflections on and suggestions for improving fieldwork. As feminists ourselves we placed a high value on sharing personal reflections on emotional challenges that the research team faced. However, our South Sudanese colleagues did not find these approaches very useful, preferring to discuss technical challenges, and placed emphasis on the importance of professionalism. This experience suggests the need for more culturally diverse feminist research tools, and for better recognition of the crucial role played by national researchers in international research projects. We end with recommendations.     

Emergence of the wrapped Cauchy distribution in mixed directional data

AStA Advances in Statistical Analysis - Inferring the most appropriate distribution (or distributions) to describe observed directional data is important in many applications of circular...