Partially linear censored quantile regression

Censored regression quantile (CRQ) methods provide a powerful and flexible approach to the analysis of censored survival data when standard linear models are felt to be appropriate. In many cases however, greater flexibility is desired to go beyond the usual multiple regression paradigm. One area of common interest is that of partially linear models: one (or more) of the explanatory covariates are assumed to act on the response through a non-linear function. Here the CRQ approach of Portnoy (J Am Stat Assoc 98:1001–1012, 2003) is extended to this partially linear setting. Basic consistency results are presented. A simulation experiment and unemployment example justify the value of the partially linear approach over methods based on the Cox proportional hazards model and on methods not permitting nonlinearity.     

Job stress,social support and health amongst shrimp fishermen

Abstract

Samples of shrimp fishermen (n = 211) and land-based workers (n = 99) drawn from a US Gulf Coast community are compared with regard to their degree of exposure to occupational stressors, level of social support, and extent of non-clinical depression and somatization. As hypothesized, shrimp fishermen report significantly greater levels of stressor exposure, support, depression and somatization at the zero-order level. At the multivariate level, with several covariates controlled, shrimpers report greater levels of stressor exposure, support and somatization. A model of the stress process which hypothesizes positive effects of stressors, and direct and indirect negative effects of social support on distress, is evaluated for each group. Occupational stressors predict as hypothesized, but social support does not. An explanation is offered which emphasizes the migratory character of shrimping as an occupation.     

Inference after variable selection using restricted permutation methods

When confronted with multiple covariates and a response variable, analysts sometimes apply a variable‐selection algorithm to the covariate‐response data to identify a subset of covariates potentially associated with the response, and then wish to make inferences about parameters in a model for the marginal association between the selected covariates and the response. If an independent data set were available, the parameters of interest could be estimated by using standard inference methods to fit the postulated marginal model to the independent data set. However, when applied to the same data set used by the variable selector, standard (“naive”) methods can lead to distorted inferences. The authors develop testing and interval estimation methods for parameters reflecting the marginal association between the selected covariates and response variable, based on the same data set used for variable selection. They provide theoretical justification for the proposed methods, present results to guide their implementation, and use simulations to assess and compare their performance to a sample‐splitting approach. The methods are illustrated with data from a recent AIDS study. The Canadian Journal of Statistics 37: 625–644; 2009 © 2009 Statistical Society of Canada     

Why the rise in adolescent fertility rates in the Dominican Republic in the 1990s?

Despite concern over high pregnancy rates and levels of risk for sexually transmittedinfections, adolescent fertility rates in the Dominican Republic have not changed substantially since the early 1980's, and actually increased during the early to mid 1990s. The present study was undertaken to assess the factors contributing to the recent rise in fertility among Dominican adolescents. The findings suggest that although contraceptive use among adolescents and young adults has increased, this has been more than offset by ominous trends on other determinants of fertility. Among these are declines in mean age at first sex and first marriage/union without a commensurate decline in mean age at first contraceptive use, and stubbornly high discontinuation rates for oral contraceptives andcondoms. There is also some evidence that rates of induced abortion among adolescents may have increased, without which adolescent fertility rates would have been even higher. Demand for children among Dominican adolescents remains strong, suggesting that efforts to reduce the current high prevalence of risky sexual behaviors need to influence social norms in order to be successful.     

The Impact of the Labor Market on Health Insurance

This paper examines the impact of labor market conditions on employer-sponsored health insurance (ESHI). Unique data from the Louisiana Health Insurance Surveys linked to unemployment data and the Louisiana Job Vacancy Surveys prior to and after Hurricane Katrina provide very large variation in the job vacancy and unemployment rates, our measures of labor market conditions. Results suggest a significant relationship between both unemployment and industry specific job vacancy rates and ESHI.     

Integrative leadership for collaborative governance: Civic engagement in Seattle

This article distills concepts and tools from the literatures on civic engagement, collaborative management, and conflict resolution into a parsimonious framework of tactics and constructs for integrative leadership. Using these tactics and constructs to compare cases of civic engagement drawn from the administration of Seattle Mayor Norman Rice (1990–98), the article demonstrates the framework's analytic potential for scholars and its strategic relevance for public leaders. The comparison of the cases suggests that the framework enables scholars and practitioners to distinguish meaningful changes in key dimensions of collaborative governance related to leadership tactics, stake holders' interpretations, and results. The conclusion proposes six hypotheses and explores theoretical implications for future research.     

The impact of macroeconomic conditions on income inequality

This paper analyzes the relationship between macroeconomic factors and the income distribution using data on equivalized disposable household income from the United Kingdom for 1961–99. We argue in favour of fitting a parametric functional form to the income distribution for each year, and then modeling the time series of model parameters in terms of the macroeconomic factors, as this better allows us to take into account non-stationarity in the time series. Estimates from models that relate income distribution parameters to cyclical variables in first differences (to account for non-stationarity) suggest that neither inflation nor unemployment have significant effects on income inequality. Compared to the commonly-used method of modelling the income shares directly, our approach indicates that there was no clear cut relationship between macroeconomic factors and the UK income distribution during the last third of the twentieth century.