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This study examined the effects on motor vehicle crashes of a policy change that led to the introduction of a very large number of off-sale alcohol outlets in Lubbock, Texas. Times-series analysis of total crashes and single-vehicle nighttime (SVN) crashes was used to compare the periods before and after the policy change in Lubbock and in a comparison area. The results of the analysis revealed some weak effects on total crashes, but no statistically significant effects were found for SVN crashes. Possible reasons for the essentially null findings of the current study regarding the effects of the policy change on motor vehicle crashes are discussed. These include the fact that there were a small number of off-sale outlets already present in the community and that motor vehicle travel immediately following alcohol consumption is less likely to occur with alcohol purchased from an off-sale outlet compared to an on-sale outlet. [ABSTRACT FROM AUTHOR]

This study assessed potential biases introduced by using maternal proxies for reporting work hazards, illness symptoms, and acute agricultural injuries in studies of migrant farmworker families. A convenience sample of 79 mother/spouse and mother/oldest child pairs was obtained from a two-year cohort study of migrant farmworker families from Starr County, Texas. Pairs completed an interviewer-administered survey including 27 close-ended items describing work history, illness symptoms, and acute injuries during the 2001 migration season. Data analysis included prevalence, sensitivity, and specificity measures. Maternal proxy reports of subjective symptoms of a spouse or child were approximately 50% lower than spouse or child self-reports. Sensitivity and specificity of mothers' responses regarding hazard items were higher for spouses than for children. For items measuring illness symptoms, sensitivity of mothers' responses for spouses and oldest child pairs was generally less than 30%; however, specificity was generally above 90%. For acute agricultural injury, the mother/spouse sensitivity was 75%, the mother/child 40%, and specificities were 100% and 97%, respectively. Sensitivity and specificity for spouse pairs was generally higher than mother/child pairs for work hazards, illness symptoms and acute injuries. While mothers may be acceptable proxies for spouses in this population, efforts should be made to collect data directly from adolescent children in studies of agricultural injuries. [ABSTRACT FROM AUTHOR]

Accelerated failure time model is a popular model to analyze censored time-to-event data. Analysis of this model without assuming any parametric distribution for the model error is challenging, and the model complexity is enhanced in the presence of large number of covariates. We developed a nonparametric Bayesian method for regularized estimation of the regression parameters in a flexible accelerated failure time model. The novelties of our method lie in modeling the error distribution of the accelerated failure time nonparametrically, modeling the variance as a function of the mean, and adopting a variable selection technique in modeling the mean. The proposed method allowed for identifying a set of important regression parameters, estimating survival probabilities, and constructing credible intervals of the survival probabilities. We evaluated operating characteristics of the proposed method via simulation studies. Finally, we apply our new comprehensive method to analyze the motivating breast cancer data from the Surveillance, Epidemiology, and End Results Program, and estimate the five-year survival probabilities for women included in the Surveillance, Epidemiology, and End Results database who were diagnosed with breast cancer between 1990 and 2000.

Little is known about academic performance, health, and social functioning of youth from migrant farmworker families. This study was designed to compare demographic, academic, health, and social data between migrant and nonmigrant youth residing in South Texas. Anonymous cross-sectional survey data were collected from 6954 middle and 3565 high school students. About 5% of South Texas middle and high school students reported belonging to a migrant family. Compared with nonmigrant students, migrant youth were more likely to miss and arrive late to school, sleep in class, and study fewer hours weekly. Migrant students reported fewer hours of nightly sleep, fewer hours spent with their friends, and more minor illnesses than nonmigrant youth. These results demonstrate the need for interventions specifically targeted to this vulnerable adolescent population.