Physical fitness effects on substance abuse risk factors and use patterns

In this study, seventy-four adolescents in either a school, community or hospital based drug intervention program received and eight to nine week structured fitness activity class as an integrated element of their respective prevention or treatment program. Prepost assessments indicated significant gains in the field fitness tests of one mile run, 1 minute situp, 1 minute pushup, percent fat and flexibility for the total sample. Based upon prepost change on the one mile run time (less than 1:00) subjects were categorized as improvers (n = 38) and non-improvers (n = 36). Improvers demonstrated a significant increase in the self concept risk factor (Piers Harris Self Concept Scale) and a significant decrease in anxiety and depression risk factors (General Well-Being Scale) compared to the non-improvers. At posttest, the improvers self reported substance use patterns were significantly lower compared to the non-improvers for percentage of the sample who were multiple drug users and alcohol uses per week and were significantly higher for the percentage of the sample demonstrating total abstinence. These findings are suggestive of the usefulness of physical training as a supplemental intervention for adolescent substance abusers.     

Income, Environmental Disamenity, and Toxic Releases

The literature argues that income growth leads to increased demand for environmental quality and thus reduction in pollution. Using a utility theoretic model, we hypothesize that the income–pollution relationship should depend on the level of disamenity of the pollutant. We proxy for disamenity using the toxicity of releases. For counties in the United States, the functional relationship between income and releases depends on the level of disamenity: the form is more concave for more toxic releases. We find that environmental improvements occur at lower levels of per capita income for more toxic pollutants.     

CONCOMITANT SCALE ESTIMATION IN REGRESSION PROBLEMS WITH INCREASING DIMENSION

We obtain Bahadur representations for the semi-interquartile range and the median deviation when these estimators are based on the residuals from a linear regression model with increasing dimension. These representations yield a variety of central limit theorems and conditions under which the two estimators are equivalent. In particular, the representations justify the use of the estimators as concomitant scale estimators in general scale equivariant M-estimation of a regression parameter when the dimension of the parameter increases with the sample size.     

Working Unusual Hours and Its Relationship to Job Satisfaction: A Study of European Maritime Pilots

Our study focuses on maritime pilotage in seven European countries and analyzes the level of job satisfaction and its predictors. Like most existing studies in the field of job satisfaction, we show that job satisfaction is an outcome of the work of maritime pilots. Stressful working conditions, such as working unsocial hours and irregular working patterns, create strains that together with intervening factors related to work, family, or the work environment ultimately reduce job satisfaction. However, our results indicate that although negative physical and social consequences are important, they are neither the strongest nor the only variables determining job satisfaction. Another effect seems more important in European maritime pilotage: Job satisfaction is instead a predictor of how much pressure and stress pilots can handle. Despite health problems and a reduction in their quality of life due to working unusual hours, most maritime pilots do not regret their choice of profession. Factors to ameliorate the working conditions are also identified. The most important parameters include alterations in working time systems, working conditions which minimize physical strain, fairness regarding payment, flexibility within the compensation system, an intensification of the possibilities for involvement and participation, an extended degree of co-determination, and the distribution of the ownership of the pilot stations.     

The Statistical Analysis of Preference Data

A new statistic and a new method of analysis are proposed for data where a sample of respondents provides a preference ordering of some treatments. The new preference statistic is compared with the Friedman statistic, particularly for an example where 12 home owners each ranked four grasses. The new analysis provides a more natural and less misleading assessment of where the differences occur than an analysis based on the rank sums of the Friedman statistic. The new analysis is also more robust to deviations from the classical location problem, is not related to election methods known to have undesirable characteristics and adheres to the Condorcet criterion for election methods.     

An R2criterion based on optimal predictors

The predictor that minimizes mean-squared prediction error is used to derive a goodness-of-fit measure that offers an asymptotically valid model selection criterion for a wide variety of regression models. In particular, a new goodness-of-fit criterion (cr²) is proposed for censored or otherwise limited dependent variables. The new goodness-of-fit measure is then applied to the analysis of duration.     

Terrestrial vertebrates in urban ecosystems: developing hypotheses for the Gwynns Falls Watershed in Baltimore,Maryland

We review the literature on terrestrial vertebrates in urban and urbanizing areas in terms of the new paradigm in ecology that focuses on the origin, spatial pattern, and current influences of habitat patches. Studies of terrestrial vertebrates have documented differences in species composition along an urban-rural gradient and have identified some of the key land use features associated with these differences. We use information from a database developed for the Gwynns Falls Watershed in Baltimore City and County, Maryland to demonstrate how a study of forest-dependent breeding birds could be used to identify mechanisms that account for differences in the bird communities of forest patches in urban areas, and to provide useful information to planners and managers involved in wildlife conservation and management.     

Semiparametric mixture models and repeated measures: the multinomial cut point model

Summary.  Suppose that we have m repeated measures on each subject, and we model the observation vectors with a finite mixture model.  We further assume that the repeated measures are conditionally independent. We present methods to estimate the shape of the component distributions along with various features of the component distributions such as the medians, means and variances. We make no distributional assumptions on the components; indeed, we allow different shapes for different components.