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.     

Life Satisfaction as a Distinguishing Indicator of College Student Functioning: Further Validation of the Two-Continua Model of Mental Health

The two-continua model of mental health contends that both psychological distress and psychological well-being make related-yet-distinct contributions to our understanding of human health and its relations with other quality of life outcomes. Using self-reported somatization, depression, and anxiety symptoms as indicators of psychological distress and self-reported life satisfaction as an indicator of psychological well-being, the present study classified participants into one of four mental-health-status groups—mentally healthy, mentally unhealthy, symptomatic yet content, or asymptomatic yet discontent—and investigated between-group differences across three key indicators of college student functioning: academic achievement, interpersonal connectedness, and physical health. Findings provide further validation for the two-continua model of mental health among college students, showing that, when considered in conjunction with clinical symptoms, life satisfaction serves as a distinguishing indicator of college students functioning across academic, social, and physical health domains—as well as a strong predictor of the absence or presence of clinical symptoms and comorbidity. Implications for theory, practice, and future research are discussed.     

Expected frequency and mean size of the paradox of new members

The paradox of new members occurs when the addition of one or more new members to a weighted voting body increases, rather than decreases, the voting power of some of the old members. Extending the computational work of Brams and Affuso (1976), the mean size of the paradox and the relative frequency of its occurrence are presented for small and moderate-size weighted voting bodies. Computational results are presented and conclusions are drawn for the two power indices of Shapley-Shubik and Banzhaf, three different decision rules, and voting bodies with or without dictator. Although the paradox cannot be dismissed as either contrived or improbable, its mean size in moderatesize voting bodies is sufficiently small to question its practical significance.     

Psychosocial Interventions for Maltreated and Violence-Exposed Children

Child sexual, physical, and emotional abuse as well as child neglect and domestic violence, community violence, and Childhood Traumatic Grief may result in significant and long-lasting emotional and behavioral difficulties. This article reviews randomized controlled studies that have assessed child mental health outcomes for maltreated and violence-exposed children. Key points of this review include the following: (1) maltreated and violence-exposed children typically experience more than one of these types of traumas; (2) effective psychosocial treatments are available to address Posttraumatic Stress Disorder (PTSD), depression, anxiety, and behavioral problems in these children; (3) it is likely that treatments which effectively reduce mental health symptoms in children exposed to one type of child maltreatment or violence exposure will also be effective for other or multiple types; and (4) mental health outcomes are not the only important outcomes to address in future treatment or intervention efforts. These future directions for treatment intervention research are addressed.     

The experience of motherhood for alienated mothers

This qualitative study examined the alienated mothers' experience of motherhood. Data were collected by in‐depth semi‐structured interviews with 10 women whose children refused any contact with them. Findings revealed one main theme, ‘Merging vs. detachment’, consisting of four subthemes or motifs in these women's narratives: (i) marriage as an illusion of salvation from an abusive home; (ii) giving birth to a child as compensation for chaotic childhood experiences; (iii) husband exploiting and abusing their sense of failing motherhood; and (iv) the husband and mother‐in‐law expelling the mother. These findings were interpreted within the framework of Bowen's theory. The interpretation suggests that impairment in the mothers' and ex‐husbands' differentiation of the self is manifest in the shattered mother–child relations and in the mothers' loss of their children in the struggle with their mothers‐in‐law. Implications for practice are included.     

The Role of Evaluator-Victim Relationships in Children's Evaluations of Peer Provocation

Second-, third-, fifth-, and sixth- grade children evaluated two hypothetical target peers in three provocation scenarios which differed as to the intent of a provocative act (Ambiguous, Accidental, Hostile). In addition to age and gender, evaluator-victim relationship was manipulated with children portrayed as being in a best friend, an acquaintance, or an enemy relationship with the victim, while the agent of the provocation was an unfamiliar peer. Evaluations were assessed in terms of attributions of aggressor's intentions, behavior response of the victim, evaluator's liking for victim, and evaluator's affect. Results indicated that older children evaluated aggressor's intentions and victim's behavior response more negatively than did younger children. Further, attributions of aggressor's intent significantly predicted the victim's subsequent behavioral response. Evaluator's affect was reported to be more negative when evaluating hostile provocation compared to accidental or ambiguous provocation and evaluators in acquaintance and enemy relationships with the victim reported liking the victim more after the provocation than before it occurred. Results are discussed in terms of the social relational and social situational influences on children's evaluations of peer interactions and the need to integrate these contextual factors in children's person perception research.     

Everyday Sexism: Evidence for Its Incidence, Nature, and Psychological Impact From Three Daily Diary Studies

Three daily diary studies were conducted to examine the incidence, nature, and impact of everyday sexism as reported by college women and men. Women experienced about one to two impactful sexist incidents per week, consisting of traditional gender role stereotypes and prejudice, demeaning and degrading comments and behaviors, and sexual objectification. These incidents affected women's psychological well-being by decreasing their comfort, increasing their feelings of anger and depression, and decreasing their state self-esteem. Although the experiences had similar effects on men's anger, depression, and state self-esteem, men reported relatively fewer sexist incidents, suggesting less overall impact on men. The results provide evidence for the phenomena of everyday prejudice and enlighten our understanding of the experience of prejudice in interpersonal encounters from the perspective of the target.