Finding checkerboard patterns via fractional 0–1 programming

Biclustering is a data mining technique used to simultaneously partition the set of samples and the set of their attributes (features) into subsets (clusters). Samples and features clustered together are supposed to have a high relevance to each other. In this paper we provide a new mathematical programming formulation for unsupervised biclustering. The proposed model involves the solution of a fractional 0–1 programming problem. A linear-mixed 0–1 reformulation as well as two heuristic-based approaches are developed. Encouraging computational results on clustering real DNA microarray data sets are presented. In addition, we also discuss theoretical computational complexity issues related to biclustering.     

International study of heavy drinking: attitudes and sociodemographic factors in university students

The authors studied the prevalence of heavy drinking among students in 21 developed and developing countries using an anonymous survey of 7,846 male and 9,892 female students aged 17 to 30 years. There were wide variations in the prevalence of drinking among countries, and the highest rates of heavy drinking (defined as 5 or more drinks for men and 4 or more drinks for women on at least 1 occasion over the past 2 weeks) were reported in Belgium, Colombia, Ireland, and Poland (men), and Ireland and England (women). Heavy drinking was associated with living away from home, having a wealthier family background, and having well-educated parents. Beliefs about the dangers to health of excessive consumption were negatively related to heavy drinking. Heavy drinking is a concern among students in several countries and is associated with greater affluence. Challenging beliefs concerning health risks is a crucial aspect of prevention in this population.     

R-squared and prediction in regression with ordered quantitative response

This paper is concerned with the use of regression methods to predict values of a response variable when that variable is naturally ordered. An application to the prediction of student examination performance is provided and it is argued that, although individual scores are unlikely to be well predicted at the extremes of the range using the conditional mean, conditional on covariates, it is possible to usefully predict where an individual is likely to feature in the rank order of performance.     

A hierarchical Bayesian model for predicting the functional consequences of amino-acid polymorphisms

Summary.  Genetic polymorphisms in deoxyribonucleic acid coding regions may have a phenotypic effect on the carrier, e.g. by influencing susceptibility to disease. Detection of deleterious mutations via association studies is hampered by the large number of candidate sites; therefore methods are needed to narrow down the search to the most promising sites. For this, a possible approach is to use structural and sequence-based information of the encoded protein to predict whether a mutation at a particular site is likely to disrupt the functionality of the protein itself. We propose a hierarchical Bayesian multivariate adaptive regression spline (BMARS) model for supervised learning in this context and assess its predictive performance by using data from mutagenesis experiments on lac repressor and lysozyme proteins. In these experiments, about 12 amino-acid substitutions were performed at each native amino-acid position and the effect on protein functionality was assessed. The training data thus consist of repeated observations at each position, which the hierarchical framework is needed to account for. The model is trained on the lac repressor data and tested on the lysozyme mutations and vice versa. In particular, we show that the hierarchical BMARS model, by allowing for the clustered nature of the data, yields lower out-of-sample misclassification rates compared with both a BMARS and a frequen-tist MARS model, a support vector machine classifier and an optimally pruned classification tree.     

Instability in patchworks of child care when moving from welfare to work

We use longitudinal, qualitative interview data collected from 38 initially welfare‐reliant women in Cleveland, Ohio to examine the factors driving instability in child‐care arrangements when women transitioned from welfare to work. Grounded theory analysis revealed that decisions about care were circumscribed by scarce social and economic resources, women went to extraordinary lengths to patch together arrangements that typically involved multiple providers, relative care was central to patchworks of care, and patchworks of child care were often highly unstable. These complex arrangements and their instability were influenced by mothers’ desires to find the most suitable arrangements for their children within resource and job constraints, dissatisfaction with providers, difficulties accessing subsidies, and changes in provider availability. Findings suggest that policymakers must consider instability in patchworks of multiple child‐care providers as they consider alternatives for meeting low‐wage working women's and children's needs for safe, affordable, accessible, and enriching nonmaternal child care.     

The Sociology of Political Representation and Deliberation

The language of democracy and citizenship is infused with a complicated idea: political representation. While political theorists have explored what representation and deliberation should be like, most research on how political discussion actually happens fails directly to address these theoretical standards. This article shows the importance of representation and deliberation to our contemporary ideas about democracy and citizenship. It shows that there is no clear line between deliberation and everyday conversation. Instead, everyday talk constitutes the foundation on top of which citizens build ideas about politics. These, in turn, are the bedrock of democratic representation.     

Housing problems experienced by recipients of child welfare services

This study uses data on the experiences of families involved with child welfare services to examine the nature of housing problems and needs among these families and whether housing status affects case outcomes. First, the article describes the housing difficulties faced by two distinct child welfare service populations: families receiving voluntary in-home services and families with children in court-ordered out-of-home care. Second, the study demonstrates the relationship between housing problems and the likelihood of family reunification for children in out-of-home care. The findings have implications for the delivery of child welfare services and the provision of housing assistance to low-income families with children.     

Strengths of Gay Male Youth: An Untold Story

This exploratory study found that gay male youths develop strengths that enable them to successfully cope with the challenges and stresses associated with their overall development. These internal and external resources were (1) protective in nature, (2) indicated the presence of resilience, and (3) assisted participants in managing their sexual orientation in adolescence. Bivariate analysis revealed participants had positive self-esteem and an internal locus of control comparable to, or better than, youths overall. Age, social support from gay, lesbian, and bisexual friends and from family, and a preadolescent sense of difference were significantly correlated with self-esteem and/or locus of control.