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1.
Proportional hazards are a common assumption when designing confirmatory clinical trials in oncology. This assumption not only affects the analysis part but also the sample size calculation. The presence of delayed effects causes a change in the hazard ratio while the trial is ongoing since at the beginning we do not observe any difference between treatment arms, and after some unknown time point, the differences between treatment arms will start to appear. Hence, the proportional hazards assumption no longer holds, and both sample size calculation and analysis methods to be used should be reconsidered. The weighted log‐rank test allows a weighting for early, middle, and late differences through the Fleming and Harrington class of weights and is proven to be more efficient when the proportional hazards assumption does not hold. The Fleming and Harrington class of weights, along with the estimated delay, can be incorporated into the sample size calculation in order to maintain the desired power once the treatment arm differences start to appear. In this article, we explore the impact of delayed effects in group sequential and adaptive group sequential designs and make an empirical evaluation in terms of power and type‐I error rate of the of the weighted log‐rank test in a simulated scenario with fixed values of the Fleming and Harrington class of weights. We also give some practical recommendations regarding which methodology should be used in the presence of delayed effects depending on certain characteristics of the trial. 相似文献
2.
Hadi Emami 《统计学通讯:理论与方法》2020,49(8):1793-1800
AbstractIn this article we develop the minimax estimation approach of general linear models to the semiparametric linear models when the parameters are simultaneously constrained by an ellipsoid and linear restrictions. Combining sample information and prior constraints the minimax estimator is obtained and compared with partially least square estimator by theoretical and simulation methods. 相似文献
3.
郭娅丽 《中北大学学报(社会科学版)》2002,(3):51-53
我院法学专业培养目标是为社会培养应用型、复合型人才 ,针对实际情况 ,作者提出应改革教学内容 ,优化课程体系 ;改革教学方法 ,完善教学手段 ;提高教师业务水平 ,加强学术梯队建设等建议。 相似文献
4.
我国已经入世,面临全球化竞争,许多企业缺乏对企业经营者有效的激励机制和约束机制,致使企业缺乏动力和制度保障,建立和健全对企业经营者的激励和约束机制成为当务之急。对此既要重视物质激励,也要重视精神激励,同时还要加强对经营者的内部约束和外部约束,并形成制度。 相似文献
5.
鲁金华 《武汉理工大学学报(社会科学版)》2003,16(4):442-444
孔子的富贵观是其思想体系的重要组成部分。孔子关于世人应否追求富贵,怎样处理富贵与道义的关系,以及富裕之后还当如何等问题在《论语》中都有论述。孔子的这些论述,对当代人们创业致富,以义求利,以及坚持经济建设与精神文明建设两手抓,仍然具有启迪作用和借鉴价值。 相似文献
6.
杨小兰 《湖南人文科技学院学报》2005,7(3):17-20
对著作权人行使网络传播权进行的合理限制是网络传播权产生、网络事业发展的必然要求,限制网络传播权应遵循效率与公平平衡统一的原则、现代化原则、国际化和本土化相结合原则、诚实信用原则和公序良俗原则。 相似文献
7.
赵建军 《武汉理工大学学报(社会科学版)》2005,18(5):657-661
审美理念系统,以其特有的知识形式反映着人类审美价值的阶位需求。文中论述了人类最有代表性的五种阶位需求,认为虽然它们都反映一定的审美本质,但从生命与价值超越角度考虑,它们的内在思想特色和精神追求,还存在着很大的区别。 相似文献
8.
通过日、唐律令官人出身制度的分析比较可以看出,古代日本的贡举(科举)实际上是作为荫位制的一种附属形式而存在,从这个侧面可以发现日、唐政体的异同,探究古代日本政治体制的发展进程。 相似文献
9.
詹珊 《湛江师范学院学报》2004,25(5):51-55
网络原创文学不大气和网络写手生存的文化背景有关,其原因有写手过于贴近生活、缺乏必要的反刍过程和写手缺乏刻骨铭心的痛苦的生存体验,以及受书写工具的制约等. 相似文献
10.
Projecting losses associated with hurricanes is a complex and difficult undertaking that is wrought with uncertainties. Hurricane Charley, which struck southwest Florida on August 13, 2004, illustrates the uncertainty of forecasting damages from these storms. Due to shifts in the track and the rapid intensification of the storm, real-time estimates grew from 2 to 3 billion dollars in losses late on August 12 to a peak of 50 billion dollars for a brief time as the storm appeared to be headed for the Tampa Bay area. The storm hit the resort areas of Charlotte Harbor near Punta Gorda and then went on to Orlando in the central part of the state, with early poststorm estimates converging on a damage estimate in the 28 to 31 billion dollars range. Comparable damage to central Florida had not been seen since Hurricane Donna in 1960. The Florida Commission on Hurricane Loss Projection Methodology (FCHLPM) has recognized the role of computer models in projecting losses from hurricanes. The FCHLPM established a professional team to perform onsite (confidential) audits of computer models developed by several different companies in the United States that seek to have their models approved for use in insurance rate filings in Florida. The team's members represent the fields of actuarial science, computer science, meteorology, statistics, and wind and structural engineering. An important part of the auditing process requires uncertainty and sensitivity analyses to be performed with the applicant's proprietary model. To influence future such analyses, an uncertainty and sensitivity analysis has been completed for loss projections arising from use of a Holland B parameter hurricane wind field model. Uncertainty analysis quantifies the expected percentage reduction in the uncertainty of wind speed and loss that is attributable to each of the input variables. 相似文献