A longitudinal examination of risk and protective factors associated with drug use and unsafe sex among young African American females

This study prospectively examined associations among multiple theoretically informed risk (e.g., depression, sexual sensation seeking, and risky peers norms) and protective factors (e.g., social support, STI knowledge, and refusal to have sex self efficacy) on unsafe sex among 715 African American adolescent females aged 15–21 who participated in an STI/HIV prevention intervention. Generalized estimating equation models were used to assess associations between baseline characteristics and sexual risk over a 12-month follow-up period. Overall risk in this population was high: at baseline, nearly a third of women reported sex under the influence of alcohol or substances; ≥ 2 partners for vaginal sex, and casual sex partners in the 60 days prior to baseline, and nearly 75% of those reporting vaginal sex used condoms inconsistently. In multivariable analysis, when risk and protective factors were simultaneously considered, higher levels of sexual sensation seeking were associated with having multiple sex partners and inconsistent condom use. Greater perception of risky peer norms was associated with a higher risk of having sex under the influence of alcohol or drugs. In addition, higher sex refusal self-efficacy was protective against having multiple; casual; and concurrent sex partners. Incorporating these salient factors into prevention programs may be critical to the development of targeted interventions for this population.     

Air pollution and depressive symptomatology: Exploratory analyses of intervening psychosocial factors

Exploratory modelling revealed associations of individual perceptions, social factors, and physical components of air pollution with depressive symptomatology. Residents of the Los Angeles Metropolitan Area who have experienced a recent, undesirable life event and who perceive poor air quality in their neighborhood have greater symptoms of depression. These effects control for socioeconomic status and prior psychological status. In addition we show that perceived air quality is a function of both toxic components of ambient air as well as individual psychosocial experiences.This research was supported by the National Institute for Mental Health (MH 28924-10A1) and the Southern California Edison Health Effects Research Laboratory (J-1909902). We thank Jean Ospital, Len Edwards, and Julian Foon for their assistance. Reprint requests should be sent to Gary Evans, Program in Social Ecology, University of California, Irvine, CA 92717.     

Modeling and Forecasting Health Expectancy: Theoretical Framework and Application

Life expectancy continues to grow in most Western countries; however, a major remaining question is whether longer life expectancy will be associated with more or fewer life years spent with poor health. Therefore, complementing forecasts of life expectancy with forecasts of health expectancies is useful. To forecast health expectancy, an extension of the stochastic extrapolative models developed for forecasting total life expectancy could be applied, but instead of projecting total mortality and using regular life tables, one could project transition probabilities between health states simultaneously and use multistate life table methods. In this article, we present a theoretical framework for a multistate life table model in which the transition probabilities depend on age and calendar time. The goal of our study is to describe a model that projects transition probabilities by the Lee-Carter method, and to illustrate how it can be used to forecast future health expectancy with prediction intervals around the estimates. We applied the method to data on the Dutch population aged 55 and older, and projected transition probabilities until 2030 to obtain forecasts of life expectancy, disability-free life expectancy, and probability of compression of disability.     

Statistical methods of risk assessment for continuous variables

Adverse health effects for continuous responses are not as easily defined as adverse health effects for binary responses. Kodell and West (1993) developed methods for defining adverse effects for continuous responses and the associated risk. Procedures were developed for finding point estimates and upper confidence limits for additional risk under the assumption of a normal distribution and quadratic mean response curve with equal variances at each dose level. In this paper, methods are developed for point estimates and upper confidence limits for additional risk at experimental doses when the equal variance assumption is relaxed. An interpolation procedure is discussed for obtaining information at doses other than the experimental doses. A small simulation study is presented to test the performance of the methods discussed.     

On the Evaluation of the Kolmogorov Statistic

At least two computer program packages, SPSS and STRATA, use simulated Bernoulli trials to draw (without replacement) a random sample of records from a finite population of records. Therefore, the size of the sample is a random variable. Two estimators of a population total under this sampling procedure are compared with the usual estimator under simple random sampling. Conditions under which the Bernoulli sampling estimators have almost the same mean squared error as the simple random-sample estimator are illustrated.     

Multiple Attribute Decision Making with Inexact Value-Function Assessment

A major issue in value-function assessment is the possibility of receiving an indefinite response from a decision maker to a question about preferences. The conventional treatment requires a single, definite response from the decision maker. This approach either assumes that response error is zero or accepts the final solution as only approximate, without knowing how approximate it might be. In this paper we examine the issue of indefinite responses, define it more precisely, and present a method for incorporating it into decision making. The method is adaptive in that it is iterative and interactive with the decision maker who, at each iteration, is provided with information regarding the potential advantage of answering more trade-off questions and/or answering questions more carefully to reduce response error. In contrast to other approaches that “force” rationality and decisiveness, we work with irrationality and indecisiveness on the part of the decision maker. The method is demonstrated for the case of concave, increasing value functions.