Exact calculation of power and sample size in bioequivalence studies using two one‐sided tests

The number of subjects in a pharmacokinetic two‐period two‐treatment crossover bioequivalence study is typically small, most often less than 60. The most common approach to testing for bioequivalence is the two one‐sided tests procedure. No explicit mathematical formula for the power function in the context of the two one‐sided tests procedure exists in the statistical literature, although the exact power based on Owen's special case of bivariate noncentral t‐distribution has been tabulated and graphed. Several approximations have previously been published for the probability of rejection in the two one‐sided tests procedure for crossover bioequivalence studies. These approximations and associated sample size formulas are reviewed in this article and compared for various parameter combinations with exact power formulas derived here, which are computed analytically as univariate integrals and which have been validated by Monte Carlo simulations. The exact formulas for power and sample size are shown to improve markedly in realistic parameter settings over the previous approximations. Copyright © 2014 John Wiley & Sons, Ltd.     

Letter to the editor by the authors of Exact Calculation of Power and Sample Size in Bioequivalence Studies Using Two One‐sided Tests,Pharmaceutical Statistics,DOI: 10.1002/pst.1666

This article reflects the views of the authors and should not be construed to be those of the US Food and Drug Administration. Copyright © 2015 John Wiley & Sons, Ltd.     

He Said What? Guided Cognitive Reframing About the Co‐Resident Father/Stepfather–Adolescent Relationship

We studied young adolescents' seeking out support to understand conflict with their co‐resident fathers/stepfathers, and the cognitive and affective implications of such support‐seeking, phenomena we call guided cognitive reframing. Our sample included 392 adolescents (M_age = 12.5, 52.3% female) who were either of Mexican or European ancestry and lived with their biological mothers and either a stepfather or a biological father. More frequent reframing was associated with more adaptive cognitive explanations for father/stepfather behavior. Cognitions explained the link between seeking out and feelings about the father/stepfather and self. Feelings about the self were more strongly linked to depressive symptoms than cognitions. We discuss the implications for future research on social support, coping, guided cognitive reframing, and father–child relationships.     

Understanding preferences for tree attributes: the relative effects of socio-economic and local environmental factors

Urban plant biodiversity is influenced by both the physical environment and attitudes and preferences of urban residents for specific plant types. Urban residents are assumed to be disconnected from their immediate environment, and cultural and societal factors have been emphasized over environmental factors in studies of landscaping choices. However, we postulate that local climatic and environmental factors can also affect preferences for plant attributes. Therefore, spatial and temporal patterns in urban tree biodiversity may be driven not only by the direct effect of environmental variables on plant function, but also by the effect of environmental variables on attitudes toward trees and associated choices about which types of trees to plant. Here, we tested the relative effects of socio-economic and local environmental factors on preferences toward tree attributes in five counties in southern California in and surrounding Los Angeles, based on 1,029 household surveys. We found that local environmental factors have as strong an effect on preferences for tree attributes as socio-economic factors. Specifically, people located in hotter climates (average maximum temperature 25.1 °C) were more likely to value shade trees than those located in cooler regions (23.1 °C). Additionally, people located in desert areas were less likely to consider trees to be important in their city compared with people located in naturally forested areas. Overall, our research demonstrates the inherent connections between local environmental factors and perceptions of nature, even in large modern cities. Accounting for these factors can contribute to the growing interest in understanding patterns of urban biodiversity.     

Transitions to adulthood in contexts of economic crisis and post-recession. The case of Argentina

The possibilities that are available to youth in contemporary Western societies are highly sophisticated and related mostly to the transition between secondary school and higher education, the first job placement, independent housing, lifestyle construction and the consumption of goods produced by cultural industries in a globalist world. Secondary education represents a main factor in terms of socialisation, training, access to employment, citizenship and youth identity construction, making it a key for public policies aimed at youth in Latin America. The article presents the initial results of a research project on transition processes from secondary school to employment in Argentina. The findings are based on statistical information and the empirical analysis of data gathered in two very different economic and social contexts: the first was one of the worst social and economic crisis in the country's history (1999–2003), and the second was a long period of economic growth and increased social welfare (2004–2012). The data are presented in response to the following question: How do different economic contexts influence the transitions of youth in different social class contexts? By answering this question, the significant role of public policies in generating better living conditions for youth becomes clear.     

The Influence of Gender Equality on Volunteering Among European Senior Citizens

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - This research analyzes how gender equality influences the participation of European senior citizens in a range of...     

Does Child Gender Predict Older Parents’ Well-Being?

Inconsistencies in comparisons of older parents’ well-being with that of older, childless adults may be resolved by considering the separate effects of sons and daughters on parents. The hypothesis was that older parents of only daughters have greater life satisfaction, more satisfying relations with their children, more intimate family relations, and greater social support satisfaction compared to older childless adults and parents of only sons. Childless older adults were predicted to have more intimate friends. The effect of having both sons and daughters was also explored. Longitudinal results indicated parents had greater life satisfaction than childless adults, and parents of daughters were more satisfied with relations with their children than parents of only sons. Childless adults had more relations with friends and fewer family intimate relations. Neither social support satisfaction or affect varied across groups. The findings are related to gender socialization, social support, and normative expectations.     

The Happiness Workout

This study tests for causality from exercise and physical activity to life satisfaction (LS) by applying an instrumental variable approach with the respondents’ perceived benefits of exercise participation as instruments. Using data across 25 countries from the Eurobarometer survey, our results confirm the positive association between exercise and LS. In terms of causality, the results indicate that being active increases LS for both gender, though more for men than women. One main reason for this relationship is that exercise is perceived as being pleasurable, something that policy-makers should keep in mind when designing programmes to get us off the sofa.     

Educational Attainment by Life Course Sexual Attraction: Prevalence and Correlates in a Nationally Representative Sample of Young Adults

Researchers know relatively little about the educational attainment of sexual minorities, despite the fact that educational attainment is consistently associated with a range of social, economic, and health outcomes. We examined whether sexual attraction in adolescence and early adulthood was associated with educational attainment in early adulthood among a nationally representative sample of US young adults. We analyzed waves I and IV restricted data from the National Longitudinal Study of Adolescent Health (n = 14,111). Sexual orientation was assessed using self-reports of romantic attraction in waves I (adolescence) and IV (adulthood). Multinomial regression models were estimated and all analyses were stratified by gender. Women attracted to the same-sex in adulthood only had lower educational attainment compared to women attracted only to the opposite-sex in adolescence and adulthood. Men attracted to the same-sex in adolescence only had lower educational attainment compared to men attracted only to the opposite-sex in adolescence and adulthood. Adolescent experiences and academic performance attenuated educational disparities among men and women. Adjustment for adolescent experiences also revealed a suppression effect; women attracted to the same-sex in adolescence and adulthood had lower predicted probabilities of having a high school diploma or less compared to women attracted only to the opposite-sex in adolescence and adulthood. Our findings challenge previous research documenting higher educational attainment among sexual minorities in the US. Additional population-based studies documenting the educational attainment of sexual-minority adults are needed.