Exact sample-size determination in testing non-inferiority under a simple crossover trial

For testing the non-inferiority (or equivalence) of an experimental treatment to a standard treatment, the odds ratio (OR) of patient response rates has been recommended to measure the relative treatment efficacy. On the basis of an exact test procedure proposed elsewhere for a simple crossover design, we develop an exact sample-size calculation procedure with respect to the OR of patient response rates for a desired power of detecting non-inferiority at a given nominal type I error. We note that the sample size calculated for a desired power based on an asymptotic test procedure can be much smaller than that based on the exact test procedure under a given situation. We further discuss the advantage and disadvantage of sample-size calculation using the exact test and the asymptotic test procedures. We employ an example by studying two inhalation devices for asthmatics to illustrate the use of sample-size calculation procedure developed here.     

Mixed estimation of old‐age mortality

The estimation of the mortality of the “oldest old”; is subject to considerable random error, but important prior information exists that can be used to make the estimates more robust. Mixed estimation is a method of incorporating auxiliary information into the statistical estimation of linear models. We extend the method to cover general maximum likelihood estimation, and show that the mixed estimator can be represented approximately as a weighted average of the purely data based estimator and the auxiliary estimator. The methods can be applied to the analysis of the old‐age mortality via logistic and Poisson regression. A major advantage of the mixed estimator is the simplicity with which it can incorporate partial prior information. Moreover, no special software is needed in the fitting. We show how the targeting methods of Coale and Kisker can be represented as mixed estimation in a natural way that is more flexible than the original proposal. We also derive empirical estimates of the target information based on pooled data from several countries with high quality data. We consider the mortality of Finland at ages 80 +, study the reliability of the evidence of mortality crossover, and derive estimates of life expectancy at age 100.     

Nonparametric approaches for comparing three-period,two-treatment,four-sequence crossover designs

The paper describes nonparametric approaches for comparing three-period, two-treatment, four-sequence crossover designs through testing the hypothesis that the treatments are interchangeable. The proposed approaches are based on a model which incorporates, along with the direct treatment effects, self and mixed carryover effects. Related asymptotic results are obtained. Comparisons among the designs are made numerically with respect to type I error rate and power of the tests considering compound symmetry and autoregressive covariance structures of the response variables. Lengths of the confidence intervals of the treatment differences are also used to make comparative study among the designs.     

Boundary-Spanning Demands,Personal Mastery,and Family Satisfaction: Individual and Crossover Effects Among Dual-Earner Parents

Grounded in ecological systems theory, this study modeled family satisfaction as a function of family-unfriendly work culture, work–family blurring, and personal mastery, examining both individual crossover effects. Analysis of data from 273 married dual-earner parents revealed that family-unfriendly work culture was negatively related to family satisfaction, whereas personal mastery was positively related to family satisfaction. Mothers' family-unfriendly work culture and work–family blurring were negatively related to their husbands' family satisfaction, but no parallel crossover findings were obtained for fathers, suggesting gender differences in crossover. Results were consistent with the notion that family life can be compromised by work cultures that create demands spanning both work and family domains. Implications for the management of work and family boundaries are discussed.     

从跨界设计的实例看创造思维的结晶

现代的任何一个领域都不是一项单一的专业所能够独立完成的,它需要跨专业的探索,因而人们越来越多的以多重身份在不同领域穿梭游走,跨界现象便出现了。它既是一种古典工作方式的复兴,也是一种新趋势的融合,强调不同领域事物的“合作、交叉”。今天的跨界已经直指各专业领域的每一处。使得原本互不相关的元素互相交汇融合,成为新的文化符号。     

医工信交叉融合推动高校医学学科发展的思考

生物医学工程专业包含很多方向, 目前很多课程还有待完善, 这在一定程度上制约了中国医工交叉类一流人才培养。从医工交叉型思维方式训练、对国外优质课程进行吸收与重构、\     

Analysing pharmacokinetic drug interaction or comparability studies with missing values in crossover design

In a pharmacokinetic drug interaction study using a three‐period, three‐treatment (drug A, drug B, and drugs A and B concomitantly) crossover design, pharmacokinetic parameters for either drug are only measured in two of the three periods. Similar missing data problems can arise for a four‐period, four‐treatment crossover pharmacokinetic comparability study. This paper investigates whether the usual ANOVA model for the crossover design can be applied under this pattern of missing data. It is shown that the model can still be used, contrary to a belief that a new one is needed. The effect of this type of missing data pattern on the statistical properties of treatment, period and carryover effect estimates was derived and illustrated by means of simulations and an example. Copyright © 2003 John Wiley & Sons, Ltd.     

证券市场分形结构与市场模型研究——国家自然科学基金项目（70371062）回溯

回顾了国家自然科学基金项目"证券市场分形结构与市场模型研究",70371062,的立项背景,介绍了项目研究的内容、主要研究成果及代表性文献,列举了项目研究所产生的社会影响及下一步的研究设想.     

A generalization of the Grizzle model to the estimation of treatment effects in crossover trials with non-compliance

Compliance with one specified dosing strategy of assigned treatments is a common problem in randomized drug clinical trials. Recently, there has been much interest in methods used for analysing treatment effects in randomized clinical trials that are subject to non-compliance. In this paper, we estimate and compare treatment effects based on the Grizzle model (GM) (ignorable non-compliance) as the custom model and the generalized Grizzle model (GGM) (non-ignorable non-compliance) as the new model. A real data set based on the treatment of knee osteoarthritis is used to compare these models. The results based on the likelihood ratio statistics and simulation study show the advantage of the proposed model (GGM) over the custom model (GGM).