Spatial heterogeneity in drinking water sources in the Greater Accra Metropolitan Area (GAMA), Ghana

Population and Environment - Universal access to safe drinking water is essential to population health and well-being, as recognized in the Sustainable Development Goals (SDG). To develop targeted...     

Quality of life indicators and health: Current status and emerging conceptions

Quality of life is an increasingly common theme in the health status and health promotion literatures. Six approaches that consider quality of life and health are reviewed. These are (a) health-related quality of life; (b) quality of life as social diagnosis in health promotion; (c) quality of life among persons with developmental disabilities; (d) quality of life as social indicators; (e) the Centre for Health Promotion (University of Toronto) model, and (f) Lindstrom's quality of life model. Each approach is considered as to its emphasis on objective or subjective indicators, individual or system-level measurement, value-laden or value-neutral assumptions, and potential relationship to social policy and social change goals. The links among the social indicators, quality of life, and health promotions areas are examined.     

Adult perpetrator gender asymmetries in child sexual assault victim selection: results from the 2000 National Incident-Based Report System

Data from the 2000 National Incident-Based Reporting System (NIBRS) show that while males make up about nine out of every 10 adult sexual assault perpetrators, totaling about 26,878 incidents within the reporting period, females account for about one out of 10 perpetrators, totaling about 1,162 incidents. Male sexual assault perpetrators offend against child victims about 25% of the time and predominantly choose female child victims, whereas female perpetrators offend against child victims about 40% of the time and choose child victims of both genders equally. Male perpetrators offend against adolescent victims about 40% of the time, and once again tend to choose female adolescent victims. Female perpetrators offend against adolescent victims a comparable amount of time (about 45%), and for forcible offenses (rape, sodomy, sexual assault with an object, and forcible fondling) choose adolescent victims of both genders equally, while for non-forcible offenses (non-forcible incest and statutory rape) they tend to choose predominantly male victims. Finally, adult male sexual assault perpetrators choose adult victims about 36% of the time while female perpetrators choose adult victims only 16% of the time. Implications for professionals are discussed, including recommendations to aid in correct identification of adult perpetrators and child/adolescent victims of sexual assault.     

Support system for management of shares ergonomic

This article discusses the development of a computerized support to demands for treatment of a wide spectrum and diverse nature. Developed under SPM platform (Situa??o, Problema e Melhoria), the practitioner seeks to provide an ergonomic aid from the identification and characterization of the processes of analysis demands. The interest of a technological support the practice of ergonomics is a domestic origin, which already features a wide universe. For purposes of this article will be drawn the line defined by the universe in the Federal Public Service occupations within the guidelines set Subsystem Integrated System for Health Care Workers of the Federal Government. The development of this system initially intended to assist the practitioner in ergonomics mapping situations in which the federal public servant has been undergoing for the second time that can classify and then treat them.     

Bayesian robust transformation and variable selection: A unified approach

The authors consider the problem of simultaneous transformation and variable selection for linear regression. They propose a fully Bayesian solution to the problem, which allows averaging over all models considered including transformations of the response and predictors. The authors use the Box‐Cox family of transformations to transform the response and each predictor. To deal with the change of scale induced by the transformations, the authors propose to focus on new quantities rather than the estimated regression coefficients. These quantities, referred to as generalized regression coefficients, have a similar interpretation to the usual regression coefficients on the original scale of the data, but do not depend on the transformations. This allows probabilistic statements about the size of the effect associated with each variable, on the original scale of the data. In addition to variable and transformation selection, there is also uncertainty involved in the identification of outliers in regression. Thus, the authors also propose a more robust model to account for such outliers based on a t‐distribution with unknown degrees of freedom. Parameter estimation is carried out using an efficient Markov chain Monte Carlo algorithm, which permits moves around the space of all possible models. Using three real data sets and a simulated study, the authors show that there is considerable uncertainty about variable selection, choice of transformation, and outlier identification, and that there is advantage in dealing with all three simultaneously. The Canadian Journal of Statistics 37: 361–380; 2009 © 2009 Statistical Society of Canada     

Using fractionalization indexes: deriving methodological principles for growth studies from time series evidence

Recent cross-country growth studies have found that ethnolinguistic fractionalization is an important explanatory variable of long-run growth performance. This paper highlights some limitations of cross-country studies by focusing on the time series evidence for South Africa. In presenting variation over time in a number of social dimensions, this paper adds longitudinal evidence on a range of dimensions that have been linked to long run economic development. Given South Africa’s history of ethnic and racial politics, it constitutes a useful case study to explore the dynamics of the possible effects of ethnolinguistic fractionalization on growth. We introduce several new sets of fractionalization indicators for South Africa: ethnolinguistic, religious and cultural fractionalization, and a polarization measure. The results of this study provide important nuance to the existing body of evidence, for the use of fractionalization indices in growth studies.

PARLIAMENT SHAPES AND SIZES

This paper proposes a model of Parliamentary institutions in which a society makes three decisions behind the veil of ignorance: whether a Parliament should comprise one or two chambers, what the relative bargaining power of each chamber should be if the Parliament is bicameral, and how many legislators should sit in each chamber. We document empirical regularities across countries that are consistent with the predictions of our model. (JEL D71, D72)     

Stress–strength reliability of a non-identical-component-strengths system based on upper record values from the family of Kumaraswamy generalized distributions

In an attempt to produce more realistic stress–strength models, this article considers the estimation of stress–strength reliability in a multi-component system with non-identical component strengths based on upper record values from the family of Kumaraswamy generalized distributions. The maximum likelihood estimator of the reliability, its asymptotic distribution and asymptotic confidence intervals are constructed. Bayes estimates under symmetric squared error loss function using conjugate prior distributions are computed and corresponding highest probability density credible intervals are also constructed. In Bayesian estimation, Lindley approximation and the Markov Chain Monte Carlo method are employed due to lack of explicit forms. For the first time using records, the uniformly minimum variance unbiased estimator and the closed form of Bayes estimator using conjugate and non-informative priors are derived for a common and known shape parameter of the stress and strength variates distributions. Comparisons of the performance of the estimators are carried out using Monte Carlo simulations, the mean squared error, bias and coverage probabilities. Finally, a demonstration is presented on how the proposed model may be utilized in materials science and engineering with the analysis of high-strength steel fatigue life data.     

Flexible mixture modeling via the multivariate t distribution with?the?Box-Cox transformation: an?alternative to?the?skew-t distribution

Cluster analysis is the automated search for groups of homogeneous observations in a data set. A popular modeling approach for clustering is based on finite normal mixture models, which assume that each cluster is modeled as a multivariate normal distribution. However, the normality assumption that each component is symmetric is often unrealistic. Furthermore, normal mixture models are not robust against outliers; they often require extra components for modeling outliers and/or give a poor representation of the data. To address these issues, we propose a new class of distributions, multivariate t distributions with the Box-Cox transformation, for mixture modeling. This class of distributions generalizes the normal distribution with the more heavy-tailed t distribution, and introduces skewness via the Box-Cox transformation. As a result, this provides a unified framework to simultaneously handle outlier identification and data transformation, two interrelated issues. We describe an Expectation-Maximization algorithm for parameter estimation along with transformation selection. We demonstrate the proposed methodology with three real data sets and simulation studies. Compared with a wealth of approaches including the skew-t mixture model, the proposed t mixture model with the Box-Cox transformation performs favorably in terms of accuracy in the assignment of observations, robustness against model misspecification, and selection of the number of components.