Design and analysis of a 3‐arm noninferiority trial with a prespecified margin for the hazard ratio

A 3‐arm trial design that includes an experimental treatment, an active reference treatment, and a placebo is useful for assessing the noninferiority of an experimental treatment. The inclusion of a placebo arm enables the assessment of assay sensitivity and internal validation, in addition to the testing of the noninferiority of the experimental treatment compared with the reference treatment. In 3‐arm noninferiority trials, various statistical test procedures have been considered to evaluate the following 3 hypotheses: (i) superiority of the experimental treatment over the placebo, (ii) superiority of the reference treatment over the placebo, and (iii) noninferiority of the experimental treatment compared with the reference treatment. However, hypothesis (ii) can be insufficient and may not accurately assess the assay sensitivity for the noninferiority of the experimental treatment compared with the reference treatment. Thus, demonstrating that the superiority of the reference treatment over the placebo is greater than the noninferiority margin (the nonsuperiority of the reference treatment compared with the placebo) can be necessary. Here, we propose log‐rank statistical procedures for evaluating data obtained from 3‐arm noninferiority trials to assess assay sensitivity with a prespecified margin Δ. In addition, we derive the approximate sample size and optimal allocation required to minimize the total sample size and that of the placebo treatment sample size, hierarchically.     

An approximation to the generalized hypergeometric distribution

A generalized hypergeometric (GHG) distribution was defined, and its higher order approximations were given by Takeuchi (1984). In this paper, an improvement on the approximation is considered and examined by the numerical calculation. Several examples including the Poisson, binomial, negative-binomial, hypergeometric and negative-hypergeometric distributions are also given.     

The study of wrist postures of musicians using the WristSystem (Greenleaf Medical System)

This study examined wrist motions of instrumentalists who have never experienced a cumulative traumatic disorder. Eighteen student musicians ranging from 18 to 29 years of age, with more than 9 years of playing experience participated in this study using the WristSystem (Greenleaf Medical System). The wrist motions were measured while participants played their instrument for five minutes. The results indicated a different pattern of wrist movements for each instrumentalist. Pianists demonstrated more ulnar deviation for both hands and more flexion for the left hand than any of the other instrumentalists. The average wrist range of motion for all four movements was under 15 degrees for violinists and violists. The right hand of the cellist had more flexion than any other instrumentalists. For both hands, flutists had more wrist extension than any other instrumentalists. This study provided information about wrist motions of musicians as one of the many factors that contribute to cumulative traumatic disorders. However, further research is needed to identify causal factors, and to promote prevention of the injury.     

Evaluation of the effects of the Aban Aya Youth Project in reducing violence among African American adolescent males using latent class growth mixture modeling techniques

This study employs growth mixture modeling techniques to evaluate the preventive effects of the Aban Aya Youth Project in reducing the rate of growth of violence among African American adolescent males (N = 552). Results suggest three distinct classes of participants: high risk (34%), medium risk (54%), and low risk (12%) based on both the participants' initial violence scores and their growth of violence over time. Results further show significant effects (almost 3 times as large as the effect found in the regular one-class analysis) for the high-risk class but not for the medium- or low-risk classes.