Sample size re‐estimation incorporating prior information on a nuisance parameter

Prior information is often incorporated informally when planning a clinical trial. Here, we present an approach on how to incorporate prior information, such as data from historical clinical trials, into the nuisance parameter–based sample size re‐estimation in a design with an internal pilot study. We focus on trials with continuous endpoints in which the outcome variance is the nuisance parameter. For planning and analyzing the trial, frequentist methods are considered. Moreover, the external information on the variance is summarized by the Bayesian meta‐analytic‐predictive approach. To incorporate external information into the sample size re‐estimation, we propose to update the meta‐analytic‐predictive prior based on the results of the internal pilot study and to re‐estimate the sample size using an estimator from the posterior. By means of a simulation study, we compare the operating characteristics such as power and sample size distribution of the proposed procedure with the traditional sample size re‐estimation approach that uses the pooled variance estimator. The simulation study shows that, if no prior‐data conflict is present, incorporating external information into the sample size re‐estimation improves the operating characteristics compared to the traditional approach. In the case of a prior‐data conflict, that is, when the variance of the ongoing clinical trial is unequal to the prior location, the performance of the traditional sample size re‐estimation procedure is in general superior, even when the prior information is robustified. When considering to include prior information in sample size re‐estimation, the potential gains should be balanced against the risks.     

岩石可钻性能量法现场实验研究

本文介绍了岩石可钻性能全法在油田现场实脸研究的成果:确定其可钻性指标凡对地层的适用范围，证明K指标比其他可钻性指标能更容易、史好地反映出井下实际地层可钻性变化情无，用K指标预浏钻速与实际钻速接近.     

生产者货币计价决定因素的实证研究

利用12个发达国家和发展中国家的非平衡面板样本数据,对微观、宏观和其他因素对生产者货币计价(PCP)的影响进行实证研究,指出经济规模、市场份额、金融市场的发达程度、币值的对内稳定性和产品差异化程度是最主要的影响因素,而出口商的谈判能力、币值的对外稳定性等因素也对PCP的选择有一定影响。根据实证检验结果,对人民币作为贸易计价货币的条件进行评估,发现其优势在于我国的经济规模、出口商的市场份额及其谈判能力以及人民币汇率的相对稳定性; 劣势在于相对落后的金融市场、不可预期性较大的通货膨胀水平以及产品的差异化程度。     

论《埤雅》声训推源

《埤雅》以声符释义贯穿全书，偶有穿凿附会之处。书中广泛运用声训之法，力求阐释事物命名之意，对声训推源进行了有益的探索，具有一定的科学性与进步性。     

Pollutant Ground Concentrations of Nonneutrally Buoyant Particles

A methodology is suggested for the estimation of the mass density and the cumulative ground deposition of a nonvolatile, nonneutrally buoyant, air pollutant (liquid or solid) released from a polluted column (following an explosion caused during routine operation in, e.g., the chemical industry or due to any kind of hostile act) and deposited on the ground via gravitational settling. In many cases, the deposited mass due to gravitational settling constitutes a significant fraction of the original inventory released from the source. Implementation of the methodology in preliminary risk assessments can serve as an efficient tool for emergency planning for both immediate and long‐term measures such as evacuation and decontamination. The methodology considers, inter alia, an estimation of the critical particle diameter, particle size, and mass distributions along the polluted column. This methodology was developed to apply in rural regions since proper application of relevant meteorological input data can be accomplished mainly for such areas.     

企业社会责任的价值相关性研究述评

以往企业社会责任的价值相关性研究的结果显示,两者间的关系是模拟两可的、矛盾的和不确定的。本文在归纳和分析国内外相关研究的多样化结果及其产生原因的基础上,从引入中介变量、考虑时间跨度和解构社会责任三个角度梳理该领域研究的新发展,并提出目前研究中急需进一步解决的问题,为未来研究提供方向性的指引。     

建安七体文论析

七体自枚乘《七发》首创之后,作者继踵。建安七体文皆是虚构一主一客问答的招隐型作品,但它们并不是简单的模拟之作,在思想倾向上,虽是以儒家思想为主,却也体现出当时对刑名之学的重视;在情感倾向上,作者的情感已由讽谏转向颂美,名为招隐,实为自招,并成为激励士人的劝仕之作;在艺术技巧上,注重语句的对仗工整,讲究音律的和谐,用典成分增多,体现出较强的骈化趋势。总之,建安七体文无论从内容还是形式,都受到了那个时代社会风气和政治背景的影响。     

基于层次分析法的多媒体教学评价研究综述

从基于层次分析法的多媒体教学评价角度,对教学条件、教学课件、课堂教学效果及实验教学等领域的多媒体教学评价进行了综述研究,就目前这些研究方向存在的问题及其发展趋势进行了点评概括.     

Pre-term Foetal Life Times in Scotland

A proportional hazards model was used to evaluate the association between ten categorical covariates and the risk of pre-term delivery for women having their first child and women in subsequent pregnancies. An adaptation of the model for use with grouped survival times made it possible to model foetal life times between 28 and 36 completed weeks of gestation for 67,000 Scottish singleton births in 1981. The use of the model was justified by testing time-dependent effects. For both groups of women age, and a history of abortion, were major factors associated with increased hazard. For women experiencing a second or higher-order birth a history of perinatal death was also associated with substantially increased hazard to the pregnancy.     

The economic design of multivariate binomial EWMA VSSI control charts

Since multi-attribute control charts have received little attention compared with multivariate variable control charts, this research is concerned with developing a new methodology to employ the multivariate exponentially weighted moving average (MEWMA) charts for m-attribute binomial processes; the attributes being the number of nonconforming items. Moreover, since the variable sample size and sampling interval (VSSI) MEWMA charts detect small process mean shifts faster than the traditional MEWMA, an economic design of the VSSI MEWMA chart is proposed to obtain the optimum design parameters of the chart. The sample size, the sampling interval, and the warning/action limit coefficients are obtained using a genetic algorithm such that the expected total cost per hour is minimized. At the end, a sensitivity analysis has been carried out to investigate the effects of the cost and the model parameters on the solution of the economic design of the VSSI MEWMA chart.