Comparison of sample size formulae for 2 × 2 cross‐over designs applied to bioequivalence studies

We consider the comparison of two formulations in terms of average bioequivalence using the 2 × 2 cross‐over design. In a bioequivalence study, the primary outcome is a pharmacokinetic measure, such as the area under the plasma concentration by time curve, which is usually assumed to have a lognormal distribution. The criterion typically used for claiming bioequivalence is that the 90% confidence interval for the ratio of the means should lie within the interval (0.80, 1.25), or equivalently the 90% confidence interval for the differences in the means on the natural log scale should be within the interval (?0.2231, 0.2231). We compare the gold standard method for calculation of the sample size based on the non‐central t distribution with those based on the central t and normal distributions. In practice, the differences between the various approaches are likely to be small. Further approximations to the power function are sometimes used to simplify the calculations. These approximations should be used with caution, because the sample size required for a desirable level of power might be under‐ or overestimated compared to the gold standard method. However, in some situations the approximate methods produce very similar sample sizes to the gold standard method. Copyright © 2005 John Wiley & Sons, Ltd.     

Intrasensory Redundancy Facilitates Infant Detection of Tempo: Extending Predictions of the Intersensory Redundancy Hypothesis

Research has demonstrated that intersensory redundancy (stimulation synchronized across multiple senses) is highly salient and facilitates processing of amodal properties in multimodal events, bootstrapping early perceptual development. The present study is the first to extend this central principle of the intersensory redundancy hypothesis (IRH) to certain types of intrasensory redundancy (stimulation synchronized within a single sense). Infants were habituated to videos of a toy hammer tapping silently (unimodal control), depicting intersensory redundancy (synchronized with a soundtrack) or intrasensory redundancy (synchronized with another visual event; light flashing or bat tapping). In Experiment 1, 2‐month‐olds showed both intersensory and intrasensory facilitation (with respect to the unimodal control) for detecting a change in tempo. However, intrasensory facilitation was found when the hammer was synchronized with the light flashing (different motion) but not with the bat tapping (same motion). Experiment 2 tested 3‐month‐olds using a somewhat easier tempo contrast. Results supported a similarity hypothesis: intrasensory redundancy between two dissimilar events was more effective than that between two similar events for promoting processing of amodal properties. These findings extend the IRH and indicate that in addition to intersensory redundancy, intrasensory redundancy between two synchronized dissimilar visual events is also effective in promoting perceptual processing of amodal event properties.     

Youth violence trajectories and proximal characteristics of intimate partner violence

Analyses first examined the developmental course of intimate partner violence (IPV), beginning with trajectories of youth violence. We then examined potential mediators of prior youth violence trajectories in models predicting later IPV perpetration as an outcome. Potential mediators include risks associated with the individual (e.g., current alcohol and drug use and mental health diagnosis), characteristics of a perpetrator's partner (e.g., use of alcohol/drugs and history of antisocial behavior), and aspects of the surrounding community (e.g., neighborhood norms favorable to violence and drug use). Data are from the Seattle Social Development Project, a longitudinal study of over 800 individuals followed from elementary school to young adulthood (age 24). Findings suggest that both chronic and late-increaser patterns of youth violence elevated the likelihood of later IPV perpetration. Partial mediation effects of the relation between youth violence and IPV were found for variables related to one's partner and the surrounding community. Individual characteristics of the perpetrator were not uniquely predictive of IPV when measured as a risk index and modeled along with other risk factors. Findings indicate that the risk of IPV could be lessened by addressing earlier forms of violence and by intervening to reduce risks within and across domains of influence.     

Single Parenting and Child Behavior Problems in Kindergarten

Two waves of data from a sample of 89 poor and near-poor single black mothers and their preschool children were used to study the influences of parenting stress, physical discipline practices, and nonresident fathers’ relations with their children on behavior problems in kindergarten. The results indicate that higher levels of parent stress, more frequent spanking, and less frequent father–child contact at time 1 were associated with increased teacher-reported behavior problems at time 2. In addition, more frequent contact between nonresident biological fathers and their children moderated the negative effect of harsh discipline by mothers on subsequent child behavior problems. Specifically, when contact with the father was low, maternal spanking resulted in elevated levels of behavior problems; with average contact, this negative effect of spanking was muted; and with high contact, spanking was not associated with increased behavior problems in kindergarten. The implications of these findings for future research and policy are discussed.     

Latino Parents’ and Adolescents’ Perceptions of the Needs and Issues of Adolescents in Their Community

Data from The Community Needs Assessment Survey were examined to understand the issues parents and adolescents felt were most important to address for the adolescents in their community. The sample of 1,784 Latino respondents consisted of 892 parent/adolescent dyads. Factor analyses found parents and adolescents identified and prioritized the same six factors: education and career planning, abuse and victimization, adolescent behavior problems, adolescent sexuality, socioeconomic stressors, and relationships. However, parent ratings for all factors were higher, indicating a higher level of concern. The article analyzes differences by age/generation (parents versus adolescents), by immigrant versus native status, and by type of dyad based on the latter (i.e., US born adolescent/US born parent, US born adolescent/immigrant parent, immigrant adolescent/immigrant parent). The authors discuss the complex interaction of these factors and the implications for practice and research.     

Using innovation to address HIV, AIDS, and environment links: intervention case studies from Zimbabwe, Uganda, and Malawi

This article presents three cross-cutting intervention case studies that address HIV, AIDS, and natural resources management in an integrated manner through innovative programming in Zimbabwe, Uganda, and Malawi. In Zimbabwe, a religious-based non-governmental group and two community organizations work together to build skills of HIV- and AIDS-vulnerable children in rural areas to meet dietary and income needs, while using natural resources sustainably. In Uganda, various government agencies and NGO actors work together to improve the food security of HIV-affected households at the national, district, sub-district, and village levels. Finally, in Malawi, a conservation organization incorporates HIV and AIDS awareness and programming into its operations and projects. Each case study presents pioneering approaches to simultaneously addressing the pressures on conservation initiatives, food security/agricultural production, income generation/livelihoods, and social and health care systems. They also provide lessons for expanding interventions and partnerships.     

Validation and Use of a Predictive Modeling Tool: Employing Scientific Findings to Improve Responsible Conduct of Research Education

Although recent evidence suggests ethics education can be effective, the nature of specific training programs, and their effectiveness, varies considerably. Building on a recent path modeling effort, the present study developed and validated a predictive modeling tool for responsible conduct of research education. The predictive modeling tool allows users to enter ratings in relation to a given ethics training program and receive instantaneous evaluative information for course refinement. Validation work suggests the tool’s predicted outcomes correlate strongly (r = 0.46) with objective course outcomes. Implications for training program development and refinement are discussed.