A modified random-effect procedure for combining risk difference in sets of 2×2 tables from clinical trials

Summary Meta-analyses of sets of clinical trials often combine risk differences from several 2×2 tables according to a random-effects model. The DerSimonian-Laird random-effects procedure, widely used for estimating the populaton mean risk difference, weights the risk difference from each primary study inversely proportional to an estimate of its variance (the sum of the between-study variance and the conditional within-study variance). Because those weights are not independent of the risk differences, however, the procedure sometimes exhibits bias and unnatural behavior. The present paper proposes a modified weighting scheme that uses the unconditional within-study variance to avoid this source of bias. The modified procedure has variance closer to that available from weighting by ideal weights when such weights are known. We studied the modified procedure in extensive simulation experiments using situations whose parameters resemble those of actual studies in medical research. For comparison we also included two unbiased procedures, the unweighted mean and a sample-size-weighted mean; their relative variability depends on the extent of heterogeneity among the primary studies. An example illustrates the application of the procedures to actual data and the differences among the results. This research was supported by Grant HS 05936 from the Agency for Health Care Policy and Research to Harvard University.     

关于线性互补问题的迭代算法

建立了一类求解线性互补问题的迭代算法。在一定条件下,研究了保证原问题的解存在唯一的充分条件,并且证明了新算法的收敛性。     

金属垂直安定面的后向散射分析

采用射线跟踪和等效电流等方法计算金属垂直安定面的后向散射场和后向散射截面积(RCS)。对TM入射和TE入射在不同的入射角下求得数值结果。仔细分析了外形对后向RCS的影响,并提出压缩后向RCS的措施。     

生理学模块教学改革初探

传统教学方法对教师和学生造成束缚,而模块式教学体现了以人为本的教学思想.在生理学理论和实验课的教学过程中,我们采用了模块式教学,尤其在实验教学中,增加了设计性实验模块.模块教学的实施和考核,注重对学生能力的培养,做到学以致用,为学习者提供了思维的空间和实践的新天地,调动了他们的积极性、主动性.     

论高校“思想道德修养”课教学方法的创新——以德育课内容为主体，将音乐融入课堂教学

"思想道德修养"作为高校"两课"中的思想品德课,要提高它的教学实效,其中最重要的一个环节就是在教学方法上创新.文章从"思想道德修养"课教学的现状、音乐的辅德优势、将音乐融入"思想道德修养"课的具体方法与优势等方面探讨了提高"思想道德修养"课教学实效的新方法,即在坚持德育课主体内容的同时,以音乐为辅助手段,将德育课内容与音乐作品有机结合.这种教学方法可以在很大程度上提高教学质量.     

蒙特卡罗方法及其在辐射剂量计算中的应用

概述了蒙特卡罗方法的产生与发展,阐述了蒙特卡罗方法的基本特点,最后就蒙特卡罗方法在辐射剂量计算上的应用进行了讨论。     

教育心理学研究方法体系的发展历程与新取向

教育心理学在其独立成为一门学科时,就借鉴自然学科的研究方法初步建立起了包括研究方法论、研究方式、具体方法和技术三层次的研究方法体系。经过学科建立20世纪到50年代的发展和60年代后的完善,逐渐形成了较为完善的教育心理学研究方法体系。在新的历史条件下,其研究方法论、方式和方法表现出综合化、生态化、科学化、本土化等发展取向。     

对“资本限量决策”方法的改进

企业面临的一类投资决策是所谓的资本限量决策,文献1给出两种解法:获利指数法和净现值法。究其实质,净现值法是一种枚举法或互斥化法,该方法可以获得最优解,但当项目个数较多时,互斥化的组合方案数很大,难以实用;计算加权获利指数工作量又很大。本文提出用差量效率指标排序法予以改进。     

Low dose risk estimation via simultaneous statistical inferences

Summary.  The paper develops and studies simultaneous confidence bounds that are useful for making low dose inferences in quantitative risk analysis. Application is intended for risk assessment studies where human, animal or ecological data are used to set safe low dose levels of a toxic agent, but where study information is limited to high dose levels of the agent. Methods are derived for estimating simultaneous, one-sided, upper confidence limits on risk for end points measured on a continuous scale. From the simultaneous confidence bounds, lower confidence limits on the dose that is associated with a particular risk (often referred to as a bench-mark dose ) are calculated. An important feature of the simultaneous construction is that any inferences that are based on inverting the simultaneous confidence bounds apply automatically to inverse bounds on the bench-mark dose.     

EXCEL的广泛应用

EXCEL电子表格处理数据的功能强大,应用简单且广泛,本文用两个例子具体阐述了EXCEL两个方面的功能。