Inferences on the Means of Two Log-Normal Distributions: A Computational Approach Test

In this article, we propose a novel approach for testing the equality of two log-normal populations using a computational approach test (CAT) that does not require explicit knowledge of the sampling distribution of the test statistic. Simulation studies demonstrate that the proposed approach can perform hypothesis testing with satisfying actual size even at small sample sizes. Overall, it is superior to other existing methods. Also, a CAT is proposed for testing about reliability of two log-normal populations when the means are the same. Simulations show that the actual size of this new approach is close to nominal level and better than the score test. At the end, the proposed methods are illustrated using two examples.     

Statistical testing strategies for assessing treatment efficacy and marker accuracy in phase III trials

When a candidate predictive marker is available, but evidence on its predictive ability is not sufficiently reliable, all‐comers trials with marker stratification are frequently conducted. We propose a framework for planning and evaluating prospective testing strategies in confirmatory, phase III marker‐stratified clinical trials based on a natural assumption on heterogeneity of treatment effects across marker‐defined subpopulations, where weak rather than strong control is permitted for multiple population tests. For phase III marker‐stratified trials, it is expected that treatment efficacy is established in a particular patient population, possibly in a marker‐defined subpopulation, and that the marker accuracy is assessed when the marker is used to restrict the indication or labelling of the treatment to a marker‐based subpopulation, ie, assessment of the clinical validity of the marker. In this paper, we develop statistical testing strategies based on criteria that are explicitly designated to the marker assessment, including those examining treatment effects in marker‐negative patients. As existing and developed statistical testing strategies can assert treatment efficacy for either the overall patient population or the marker‐positive subpopulation, we also develop criteria for evaluating the operating characteristics of the statistical testing strategies based on the probabilities of asserting treatment efficacy across marker subpopulations. Numerical evaluations to compare the statistical testing strategies based on the developed criteria are provided.     

Blinded continuous monitoring in clinical trials with recurrent event endpoints

In studies with recurrent event endpoints, misspecified assumptions of event rates or dispersion can lead to underpowered trials or overexposure of patients. Specification of overdispersion is often a particular problem as it is usually not reported in clinical trial publications. Changing event rates over the years have been described for some diseases, adding to the uncertainty in planning. To mitigate the risks of inadequate sample sizes, internal pilot study designs have been proposed with a preference for blinded sample size reestimation procedures, as they generally do not affect the type I error rate and maintain trial integrity. Blinded sample size reestimation procedures are available for trials with recurrent events as endpoints. However, the variance in the reestimated sample size can be considerable in particular with early sample size reviews. Motivated by a randomized controlled trial in paediatric multiple sclerosis, a rare neurological condition in children, we apply the concept of blinded continuous monitoring of information, which is known to reduce the variance in the resulting sample size. Assuming negative binomial distributions for the counts of recurrent relapses, we derive information criteria and propose blinded continuous monitoring procedures. The operating characteristics of these are assessed in Monte Carlo trial simulations demonstrating favourable properties with regard to type I error rate, power, and stopping time, ie, sample size.     

Modifications of sequential designs in bioequivalence trials

Bioequivalence (BE) studies are designed to show that two formulations of one drug are equivalent and they play an important role in drug development. When in a design stage, it is possible that there is a high degree of uncertainty on variability of the formulations and the actual performance of the test versus reference formulation. Therefore, an interim look may be desirable to stop the study if there is no chance of claiming BE at the end (futility), or claim BE if evidence is sufficient (efficacy), or adjust the sample size. Sequential design approaches specially for BE studies have been proposed previously in publications. We applied modification to the existing methods focusing on simplified multiplicity adjustment and futility stopping. We name our method modified sequential design for BE studies (MSDBE). Simulation results demonstrate comparable performance between MSDBE and the original published methods while MSDBE offers more transparency and better applicability. The R package MSDBE is available at https://sites.google.com/site/modsdbe/ . Copyright © 2015 John Wiley & Sons, Ltd.     

南宁市粮食生产影响因素分析

本文以南宁市为例,运用灰色关联度和生产函数,分析了1997-2003年粮食生产的影响因素及其贡献率。粮食产量灰色关联度分析作出关联因子排序:粮食单产>耕地面积>粮食作物播种面积>化肥施用量>有效灌溉面积>农村用电量>农业机械总动力>农药施用量,表明粮食单产、耕地面积与粮食作物播种面积对粮食总产的影响最大,从投入角度分析粮食总产与化肥施用量、有效灌溉面积关联度大;基于生产函数的贡献率分析表明:化肥施用量、农业科技进步、粮食播种面积、农业机械总动力、有效灌溉面积、农业劳动力对粮食增长的贡献率分别为40.08%、27.62%、12.12%、10.78%、8.91%、0.49%,说明7年来粮食增长主要依靠化肥投入、农业科技进步,农业劳动力对粮食产量增加作用微小。     

"民官比"不是影响政治体制改革的重要因素

在政治体制改革中,公务员或国家干部人数的多少并不是一个关键因素,重要的是必须把政府的社会定位(包括角色、权力和责任)划分清楚。与世界各国相比较,我国197.69∶1(或116.27∶1)的“民官比”并不高,因此,今后的政治体制改革不需要再把精力集中在“精简”上,而应按邓小平的部署,首先把党政分开和权力下放的工作做好。毕竟“小政府”是指“政府权力受限制”,而非“人数更少”;“大社会”是指“社会权利更广泛”,而非“人数更多”。     

汉代边郡军粮廪给问题探讨

粮食供给是军队后勤给养中的一项重要内容。汉代边塞地区军粮主要供给吏卒及其家属,也用于借贷和马、牛、驼、狗之食。从量制、时制、身份差别、劳动强度和年龄、性别等方面,分析了军队吏卒和吏卒家属口粮分等廪给的具体情况及其影响要素,从而揭示出汉代军粮供给体制的内在规律。正是由于汉代军粮廪给有章可循,才最大限度地提高了后勤的供应能力和军队的战斗力,保证了军队平时守土卫边和战时有效打击来犯之敌。     

中小企业信用担保与信用环境建设的研究

市场经济条件下中小企业信用担保机构的运作模式应采用政府组建，市场化运作或混合组建，市场化运作；其组织形式应是事业法人制；其运作规则应为公平、多元、规范、稳健。从担保基金的盈亏上看，决定担保规模的因素实质上是一个地区企业的总体信用状况，创造良好的信用环境将成为中小企业信用担保机构生存和发展的关键之所在。加强法制建设、社会征信机构建设和企业伦理建设是实现这一目标的基本途径。     

住宅户型设计探讨

近年来我国住宅建设日趋兴盛，住宅成为居民新的消费热点，住宅设计进入新的发展阶段，本文比较与研究已建住宅的优点与不足，探讨住宅户型设计在现阶段的重要性，设计原则及应关注的问题。