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.     

From “what works” to “making it work”: A practice perspective on evidence-based standardization in frontline service organizations

Evidence-based standards are becoming increasingly influential in frontline services connected to labor market inclusion of vulnerable citizens. To increase our understanding of standardization in such public service delivery, this study draws on interviews and ethnographic fieldwork from two frontline offices in the Norwegian Labour and Welfare Administration (2017–2018) that use the evidence-based Individual Placement and Support (IPS) standard. Adopting a theoretical perspective of organizational practices, the study highlights two distinct approaches to practicing IPS in the frontline organizations: as a “practice shift” in one organization (i.e., creating and legitimizing radically new service practices involving closer collaboration with employers) and as a “practice revival” in the other (i.e., reinstating more traditional service practices involving a holistic client orientation). Each approach relates to a specific constellation of recruitment practices, dynamics between frontline supervisors and staff, and team integration. The study contributes to the literature in two ways. First, it shows the underlying flexibility embedded in standardization and how standards may be implemented and adapted in ways that may either promote more radical change or revive traditional practices. Second, it nuances positions in the literature on the impact of standards on professional service work. On this basis, the study suggests broadening the attention in research on evidence-based standards in public service delivery from discussions of “what works” to understanding the broader organizational dynamics involved in “making it work.”     

The impact of risk aversion and ambiguity aversion on annuity and saving choices

Journal of Risk and Uncertainty - We analyze the impact of risk aversion and ambiguity aversion on the competing demands for annuities and bequeathable savings using a lifecycle recursive utility...     

Family Transitions,Economic Status,and Voter Turnout Among African‐American Inner‐City Women*

Objectives. We examine voter turnout of inner‐city African‐American mothers, many of whom are single parents and endure long‐term, economic hardship. Previous research suggests that income is a more important factor among these groups than in the general population. We seek to understand the interplay of family structure, income, and voter turnout. Methods. We explore these ideas using panel data on 754 mothers living in Chicago and interviewed as part of the 1967–1976 Woodlawn Community Study. Results. We find that marital status has no effect when women are younger but over time single parents' turnout falls behind that of married parents. This is primarily due to factors related to income and income change. Conclusions. Single mothers have lower rates of participation and, given the high rates of single parenthood in segregated inner‐city neighborhoods, this substantially diminishes the political voice of the nation's poor, contributing to class bias in the electorate.     

Examining reports and policies on cognitive enhancement: approaches, rationale, and recommendations

The phenomenon of cognitive enhancement is attracting attention in bioethics literature and beyond, in public policy. In response, three bodies--the British Medical Association (BMA); the Commission de l'éthique de la Science et de la technologie (CEST) du Québec; the American Academy of Neurology (AAN)--have produced reports and guidance on this topic. To gain insights into different public policy approaches, rationales, and recommendations on the topic, we analyzed these reports in depth. We found convergence on the definition (with the exception of the CEST) of cognitive enhancement. However, we noted a lack of critical reflection with respect to the underlying rationale for developing these reports, i.e., that cognitive enhancement practices are rampant and represent major social changes. As it currently stands, cognitive enhancement is constituted in a way that challenges the creation of coherent and effective policy recommendations. However, policy makers should not simply wait for definitional consensus and hope that on balance the benefits turn out to be greater than the risks. Some components of cognitive enhancement could be reduced down to clearly identified policy targets to be further examined. Then, if appropriate, policy should be created that is, amongst other criteria, beneficial to the majority of the population.     

The individual rationality of maintaining a sense of justice

Let us say that an individual possesses aprincipled preference if she prefers satisfying her preferences without violating the principles of justice governing her community to satisfying her preferences by violating these principles. Although living among possessors of principled preferences benefits individuals, maintaining such a preference is individually costly. Further, individuals can benefit from others possessing principled preferences without themselves possessing one. In this paper, I argue that occupying a choice situation which mirrors key aspects of our own situation, maximizing rationality requires individuals to develop and maintain principled preferences.To establish that maintaining a principled preference is individually rational for the occupants of such a choice situation, I define a range of individual strategies for them, model their choice of individual strategies as a game, and argue that this game involves an equilibrium in which all of its participants would choose to develop and maintain a principled preference.     

Exploratory Study on Drug Users’ Perspectives on Quality of Life: More than Health-Related Quality of Life?

In drug treatment outcome literature, a focus on objective and socially desirable indicators of change (e.g. no drug use) has predominated, while outcome indicators that are important for drug users themselves (e.g. quality of life, satisfaction with treatment) have largely been neglected. Nonetheless, Quality of Life (QoL) has become an important concept to evaluate effectiveness of treatment in mental health care research and disability studies. Given the almost exclusive focus on Health-related Quality of Life (HRQOL) in substance abuse research and the neglect of clients’ perspectives in this field, we explore in this study the concept of QoL as perceived by drug users. Focus group discussions (n = 9) were organised in various treatment settings and community services for drug users in the region of Ghent, Belgium to identify important dimensions of QoL and their interpretation by drug users. Data were clustered and analysed based on the theoretical framework of Robert Schalock (Quality of life. Volume 1: Conceptualization and measurement, 1996). The domains ‘personal relationships’, ‘social inclusion’ and ‘self-determination’ were discussed most frequently by the participants. They stressed the importance of a supportive social network in particular. It can be concluded that QoL is not primarily associated by drug users with health and it involves much more than the aspects typically represented in measures of HRQOL.     

Seroadaptive Strategies of Vancouver Gay and Bisexual Men in a Treatment as Prevention Environment

British Columbia’s treatment as prevention policy has provided free access to highly active antiretroviral therapy (HAART) to all HIV-positive provincial residents since 1996. One outcome is an increase in HIV-positive gay and bisexual men (GBM) with suppressed viral loads. Previous cross-sectional analyses indicated that some Vancouver GBM now recognize condomless anal sex with men on HAART who report a suppressed viral load as a seroadaptive strategy. To test the hypothesis that this new strategy, termed viral load sorting (VLS), is recognized and used among by GBM in the Momentum Health Study, we analyzed longitudinal data for HIV-negative/unknown (n = 556) and HIV-positive (n = 218) serostatus participants. Analyses indicated that both groups reported VLS, and that serostatus and Treatment Optimism Scale scores were significant determinants in frequency and use. Results exemplify the medicalization of sex and Rogers’ Diffusion Of Preventative Innovations Model, and they have important implications for HIV research and GBM sexual decision-making.