Optimizing out-of-school time: the role of free-choice learning

Free-choice learning, a new paradigm for the learning that youth and their families engage in outside school, can play an important role in the healthy development of youth, their families, and communities.     

Consumer Selection of Food-Safety Information Sources

The aim of this study is to examine the preferences of consumers for different information sources when they have a question about food safety. On the basis of a nationally representative survey conducted in the Netherlands, five distinct consumer groups are identified that not only differ on the reported use of information sources but also regarding several personality characteristics and sociodemographic variables. The empirical results show that two-thirds of the consumers are selective in their use of information sources and prefer either institutional or social sources. So, multiple information-acquisition patterns exist among the general public. The study illustrates how these findings can help to develop effective risk communication strategies.     

Symptoms of Mental Health Problems: Children’s and Adolescents’ Understandings and Implications for Gender Differences in Help Seeking

Amidst concerns that young people’s mental health is deteriorating, it is important to explore their understandings of symptoms of mental health problems and beliefs around help seeking. Drawing on focus group data from Scottish school pupils, we demonstrate how they understood symptoms of mental health problems and how their characterisations of these symptoms as ‘rare’ and ‘weird’ informed participants’ perceptions that peers, teachers and parents would respond to disclosure in stigmatising ways. Consequently, participants suggested that they would delay or avoid disclosing symptoms of mental health problems. We highlight subtle gender and age differences and outline implications for policy and practice.     

Biology,Social Environment,and Health: How Family History and Social Conditions Affect Adult Asthma*

Objective. We examine how multiple measures of both biological (family history of asthma) and social risk factors (home environment quality, socioeconomic status, and demographic characteristics) influence asthma risk among U.S. adults. Method. Using logistic regression models, we analyze data from a sample of 6,337 adults from the 2003–2004 National Asthma Survey. Results. Prevalence rates of current asthma are four times higher among adults with a family history of asthma, and the odds of having asthma are influenced most strongly by having asthmatic parents or grandparents (and, to a lesser extent, asthmatic siblings). We also find that social factors, especially characteristics of the home environment, significantly increase the odds of suffering from asthma as an adult. Conclusion. Our results show that all measures of family history are strongly linked to adult asthma prevalence, even when social factors are controlled. Social factors are also important, but very little of this is as a mediating influence that links family history and adult asthma; rather, family and social conditions have mostly independent effects.     

Bayesian semiparametric inference for the accelerated failure-time model

Bayesian semiparametric inference is considered for a loglinear model. This model consists of a parametric component for the regression coefficients and a nonparametric component for the unknown error distribution. Bayesian analysis is studied for the case of a parametric prior on the regression coefficients and a mixture-of-Dirichlet-processes prior on the unknown error distribution. A Markov-chain Monte Carlo (MCMC) method is developed to compute the features of the posterior distribution. A model selection method for obtaining a more parsimonious set of predictors is studied. The method adds indicator variables to the regression equation. The set of indicator variables represents all the possible subsets to be considered. A MCMC method is developed to search stochastically for the best subset. These procedures are applied to two examples, one with censored data.     

A direct derivation of the REML likelihood function

The original derivation of the widely cited form of the REML likelihood function for mixed linear models is difficult and indirect. This paper derives it directly using familiar operations with matrices and determinants.     

Race Differences in Sexual Behavior and Their Demographic Implications

Differences between blacks and whites in sexual behavior posited in Rushton's theory of r-K race differences were examined in the United States in an analysis of the annual surveys of the National Opinion Research Center for 1990–1996. This data set was analysed for black-white differences in numbers of sexual partners during the last 5 years and for frequency of sexual intercourse. The general pattern of the results was for blacks to report more sexual partners than whites and for black males to report greater frequency of sexual intercourse, consistent with Rushton's theory. This result has implications for the control of the AIDS epidemic and for the demographic transition among blacks.     

Methodological Approaches to Assessing Risk Perceptions Associated with Food-Related Hazards

The psychometric approach developed by Slovic and his co-workers has been effectively used to assess risk perceptions associated with different food-related hazards. However, further examination (using questionnaire data and partial correlation techniques) has indicated that technological hazards are highly differentiated from lifestyle hazards, in terms of both hazard control and knowledge about the hazard. Optimistic bias was also seen to vary between hazards. Further research has focused on a particular hazard, genetic engineering. Risk perceptions associated with genetic engineering are underpinned by ethical concern and questions relating to perceived need for the technology, as well as perceptions of risk or harm. However, increasing the specificity of hazard stimuli was found to alter the factor structure of underlying risk perceptions. The utility of preference mapping procedures in determining individual differences in trust in risk regulators is also discussed.