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...     

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.     

Designing fractional two-level experiments with nested error structures

A common feature of experiments with a random blocking factor and splitplot experiments is their nested error structure. This paper proposes a general strategy to handle fractional two-level experiments with such error structures. The strategy aims to create error strata with sufficient numbers of contrasts to separate active effects from inactive effects. The strategy also details the construction of treatment generators, given the constraints of a predetermined error structure. The key elements of the strategy are illustrated with a chemical experiment that has 16 factors and 32 runs blocked according to working days, and a cheese-making experiment that has 11 factors and 128 runs, divided over milk supplies as whole plots, curds productions as subplots and sets of identically treated cheeses as sub-subplots.     

Sport and disability: Pistorius does not fit with the categories

Oscar Pistorius presents a major issue to sports organisations, as exposed in the media. First and foremost, media wrongly perceive him as the first disabled athlete to participate in the Olympic Games. Second, they openly question the legitimacy of his participation mainly based on the inequity introduced by his prosthetic legs. Content analysis, in English and French, of written press, International Association of Athletics Federations (IAAF) and Court of Arbitration for Sport (CAS) texts, from 2004 to 2012, confirms that Pistorius presents a new puzzle to sports organizations. This is partly because they are not able to determine whether his performances are a result of his body strength or if they are biased by his artificial limbs. Furthermore, when he is competing against able-bodied athletes, sports organizsations put him in a ‘monstrous’ position. Similarly, while categorising him as an ‘athlete’ they do not grant him the characteristic feature of this category: certified comparability of performances to ultimately establish ranks.