Raising awareness of psychosocial factors in the occurrence of low back symptoms in developing countries

Although there is strong evidence that single physical, psychosocial and organisational risk factors are each independent predictors of low back symptoms (LBS), little is known about their combination/interaction, particularly in those working in developing countries. A total of 1294 Indonesian coal mining industry workers reported information about physical, psychosocial, and organisational factors using self-reported questionnaires and were placed into one of four combination exposure groups: 1) high physical (working with bent trunk; whole body vibration exposure; lifting) and high psychosocial (high effort; low reward; work stress), 2) high physical and low psychosocial, 3) low physical and high psychosocial, and 4) low physical and low psychosocial (as the reference group). The odds of LBS in the high physical and high psychosocial group was 5.15 times (95% confidence interval 2.69-9.86) that of the reference group. Psychosocial factors played a more important role than physical factors in increasing the likelihood of reporting LBS. Permanent and night shift workers were more likely to report LBS. These findings imply that efforts to reduce LBS in this workplace should address both psychosocial and physical factors but psychosocial factors should be the priority, with a special focus on permanent and night shift workers.     

The effects of family stressors on substance use initiation in adolescence

Smoking and drinking are critical problems in adolescence that have long-term adverse impacts on health and socio-economic factors. We examine the extent to which family stresses influence the timing of initiation of smoking and drinking. Using national panel data from the National Educational Longitudinal Study (NELS) we capitalize on the survey design and use school-level fixed effects that control for the local environments, including prices of cigarettes and alcohol. In addition, we narrow our control group to classmates who will experience a similar stressor in the future. We find that a composite measure of family stressors when young increases the likelihood of initiating tobacco and alcohol use, with much of the impact attributable to parental divorce. In our baseline estimates, the composite stress measure is associated with a 30% increase in the likelihood of smoking and a 20% increase in drinking. When we control for multiple sources of confounding, the impact shrinks and remains significant for smoking but not for drinking. We conclude that studies which do not control for confounding are likely to significantly overestimate the impact of family stress on substance use. Our approach helps to move the literature forward by separating causal results from spurious associations.     

Strength in Diversity? Group Heterogeneity in the Mobilization of Grassroots Organizations

Grassroots groups often find that they need to manage issues of diversity along racial/ethnic, class, gender, religious, and/or citizenship lines, among several other axes of difference. There are strong reasons to expect that diversity is a benefit to such groups, especially in terms of coalition breadth and the widely held expectation that internal heterogeneity helps organizations to resolve collective action dilemmas. Nonetheless, a long tradition within sociological research sets out the expectation that group heterogeneity thwarts the formation of collective identities and group solidarity, and therefore limits the potential for effective organizing. With a particular emphasis on groups active in local community‐based organizing since the 1970s, we review studies on a variety of features of group diversity and their effects on mobilizing processes. We find that although researchers remain somewhat divided on these critical issues, the preponderance of evidence suggests that managing diversity poses significant challenges for grassroots organizing efforts. While these challenges may not easily be overcome, we point to a variety of cases in which group differences offered a significant asset to social change efforts.     

A Bayesian approach to non-parametric monotone function estimation

Summary.  The paper proposes two Bayesian approaches to non-parametric monotone function estimation. The first approach uses a hierarchical Bayes framework and a characterization of smooth monotone functions given by Ramsay that allows unconstrained estimation. The second approach uses a Bayesian regression spline model of Smith and Kohn with a mixture distribution of constrained normal distributions as the prior for the regression coefficients to ensure the monotonicity of the resulting function estimate. The small sample properties of the two function estimators across a range of functions are provided via simulation and compared with existing methods. Asymptotic results are also given that show that Bayesian methods provide consistent function estimators for a large class of smooth functions. An example is provided involving economic demand functions that illustrates the application of the constrained regression spline estimator in the context of a multiple-regression model where two functions are constrained to be monotone.     

美的三次方

赏雪景,看礼花,品美食,观走秀。在这个时尚的夜晚,迷醉。     

An Improved Boxplot for Univariate Data

The boxplot is an effective data-visualization tool useful in diverse applications and disciplines. Although more sophisticated graphical methods exist, the boxplot remains relevant due to its simplicity, interpretability, and usefulness, even in the age of big data. This article highlights the origins and developments of the boxplot that is now widely viewed as an industry standard as well as its inherent limitations when dealing with data from skewed distributions, particularly when detecting outliers. The proposed Ratio-Skewed boxplot is shown to be practical and suitable for outlier labeling across several parametric distributions.     

Education and the changing shape of the income gradient in health

Research on the social determinants of health has increasingly sought to understand the relative importance of different features of socioeconomic status. Much of the ensuing debate has wavered between education and income, with recent research leaning increasingly toward income. This research has not, however, consistently explored interactions between different features of socioeconomic status and, in trying to understand the independent effects of different components of socioeconomic status, may have missed important features of socioeconomic position. With an eye toward examining how features of socioeconomic status combine and coalesce, this paper examines variation in the income-health association by level of education. Theories derived both from medical sociology and health economics suggest synergistic interactions between income and education, but they are unclear as to the direction and magnitude of these interactions. Results from two large and nationally representative data sets (the 1996-1997 Community Tracking Study and the 1972-2000 General Social Survey) indicate that the positive relationship between income and health varies substantially in both its strength and shape by level of education. Education improves health, and its effects are larger at lower levels of income. Moreover, education reduces the strength and curvature of the income-health relationship. Consequently, those with more education have better health for all levels of income, and fewer income-based disparities exist among the well educated than among the less well educated. The linear "gradient" relationship between income and health is, thus, more characteristic of groups with higher levels of education. Additional analyses indicate that these interactions existed in the United States in each of the last three decades. The results are discussed in light of theory regarding the perpetuation of health disparities, as well as current debates regarding the apparent incompatibility of distributive versus aggregative goals in health policy.