Sample size calculation based on risk ratio under multiple matching

To increase the efficiency of comparisons between treatments in clinical trials, we may consider the use of a multiple matching design, in which, for each patient receiving the experimental treatment, we match with more than one patient receiving the standard treatment. To assess the efficacy of the experimental treatment, the risk ratio (RR) of patient responses between two treatments is certainly one of the most commonly used measures. Because the probability of patient responses in clinical trial is often not small, the odds ratio (OR), of which the practical interpretation is not easily understood, cannot approximate RR well. Thus, all sample size formulae in terms of OR for case-control studies with multiple matched controls per case can be of limited use here. In this paper, we develop three sample size formulae based on RR for randomized trials with multiple matching. We propose a test statistic for testing the equality of RR under multiple matching. On the basis of Monte Carlo simulation, we evaluate the performance of the proposed test statistic with respect to Type I error. To evaluate the accuracy and usefulness of the three sample size formulae developed in this paper, we further calculate their simulated powers and compare them with those of the sample size formula ignoring matching and the sample size formula based on OR for multiple matching published elsewhere. Finally, we include an example that employs the multiple matching study design about the use of the supplemental ascorbate in the supportive treatment of terminal cancer patients to illustrate the use of these formulae.     

多媒体教学误区分析

近几年,我国高等学校多媒体教学的应用如雨后春笋,呈现一派蒸蒸日上的新气象。虽然多媒体技术与课程整合的观念能够被广大教师所接受,但是在大部分学校的实践过程中还普遍存在着这样那样的误区。作者通过对这些现象的分析,指出了目前多媒体教学中应注意的问题和发展方向。     

禽康灵对鸡防病助长的效应观察

禽康灵为纯中药复方制剂,对鸡具有防病助长的作用。试验表明,应用禽康灵的鸡发病率、死亡率均低于空白对照组,分别低25.22％、11.17％;试验中,试验组各批各小组平均体重较空白对照组多增重24.5g、91.0g、108.0g、10.5g、24.3g和61.2g。     

Rhetoric to Action: A Study of Stakeholder Perceptions of Aging Well in Two Local Communities

This qualitative study of local perceptions of policy goals and action in relation to aging reports 31 stakeholder interviews within 2 Australian communities exploring (a) the meaning of aging well; and (b) preferred policy actions to achieve positive aging outcomes. Findings suggest that community perceptions of aging well are broadly consistent with the goals of national and international policy frameworks in focusing on 3 dimensions—health, social engagement, and security. Further, participants believe that achievement of positive aging outcomes requires a mix of self-help, community action, and government intervention—particularly government support and encouragement for aging well initiatives.     

羊毛细度候选基因的研究进展

随着分子生物学的快速发展,各种分子标记技术在许多领域得到了广泛的应用。羊毛细度一直以来是制约我国羊毛产品的主要因素,本文论述了用KAP和KRT基因作为羊毛细度候选基因的理论依据,并阐述通过PCR-SSCP分子标记的方法对羊毛细度进行分析的可能性。     

光温条件对高产夏玉米产量及产量性状的影响

采用区域试验方法研究了光温条件对高产夏玉米产量及产量性状的影响。结果表明,同一播期穗粒数以临淄点最高,千粒重和产量由西往东依次递减。穗粒数和产量随播期延迟而降低。生育期间的积温与产量性状呈极显著正相关。开花至成熟阶段的日平均温差与千粒重及产量呈极显著负相关。高产夏玉米全生育期需积温2530℃,日照700小时;开花至成熟阶段需积温1150℃,只照330小时。     

Notes on interval estimation of the proportion ratio under a three-treatment three-period crossover trial

When comparing two experimental treatments with a placebo, we focus our attention on interval estimation of the proportion ratio (PR) of patient responses under a three-period crossover design. We propose a random effects exponential multiplicative risk model and derive asymptotic interval estimators in closed form for the PR between treatments and placebo. Using Monte Carlo simulations, we compare the performance of these interval estimators in a variety of situations. We use the data comparing two different doses of an analgesic with placebo for the relief of primary dysmenorrhea to illustrate the use of these interval estimators and the difference in estimates of the PR and odds ratio (OR) when the underlying relief rates are not small.     

Notes on estimation of the proportion ratio in the presence of carryover effects under the AB/BA crossover trial

The authors focus discussion on estimation of the proportion ratio (PR) in the presence of residual effects under the AB/BA design. Under a random effects multiplicative risk model, we develop three point estimators and three interval estimators accounting for residual effects for the PR. Using Monte Carlo simulations, we compare the performance of these point (or interval) estimators with point (or interval) estimators assuming no residual effects with respect to the bias and mean-squared-error (or the coverage probability and average length). The authors use the data taken from an AB/BA trial comparing two new inhalation devices to illustrate the use of these estimators.     

Notes on the two-stage procedure under an incomplete block two-period crossover design

Abstract

Under an incomplete block crossover design with two periods, we derive the least-squares estimators for the period effect, treatment effects and carry-over effects in explicit formulae based on within-patient differences. Using the commonly-used strategy of searching a base model for making inferences in regression analysis, we define a two-stage test procedure in studying treatment effects. On the basis of Monte Carlo simulation, we evaluate the performance of the two-stage procedure for hypothesis testing, point and interval estimation of treatment effects in a variety of situations. We note that use of the two-stage procedure can be potentially misleading and hence one should not apply a test procedure to exclusively determine whether he/she needs to account for the carry-over effect in studying treatment effects. We use the double-blind crossover trial comparing two different doses of formoterol with placebo on the forced expiratory volume in 1 second (FEV₁) readings to illustrate the use of the two-stage procedure, as well as the distinction between use of two-stage procedure and the approach with assuming no carry-over effects based on one's subjective knowledge.     

Population programme of China]

Results of population programs started in China during the last decade have attracted worldwide attention. The Chinese population issues are important due to the following characteristics: 1) China is the most populated country in the world, with over 1 billion people (22% of world population), by the end of 1980; 2) its population is 80% rural; 3) despite improved living conditions that have helped lower the mortality rate from over 20/1000 before Liberation to 10/1000 in the 1960s and finally 6-8/1000 during the last decade, the Chinese population has increased from 540 million soon after Liberation to the current 1 billion, with an average yearly growth rate of 2%; 4) China has a young population, with 36.8% under 14 years old and less than 5% over 65, hence education and employment are big issues; and 5) due to longterm backward economy resulting from feudal and colonial influence before Liberation, efforts in developing a strong Chinese economy have met with many obstacles. The above 5 features of the Chinese population have important bearing on solving China's population problems and in building its economy, developing its society, and realizing its 4 modernizations. Although China is self-sufficient despite its large population, it faces many problems and challenges especially in the areas of educating its young population and subsequent employment. To achieve a strong economy and to improve the welfare of its people, China has put efforts into controlling the size and improving the quality of its population during the past decade. Programs in population control will continue to take priority in China.