Type I error rates from likelihood‐based repeated measures analyses of incomplete longitudinal data

The last observation carried forward (LOCF) approach is commonly utilized to handle missing values in the primary analysis of clinical trials. However, recent evidence suggests that likelihood‐based analyses developed under the missing at random (MAR) framework are sensible alternatives. The objective of this study was to assess the Type I error rates from a likelihood‐based MAR approach – mixed‐model repeated measures (MMRM) – compared with LOCF when estimating treatment contrasts for mean change from baseline to endpoint (Δ). Data emulating neuropsychiatric clinical trials were simulated in a 4 × 4 factorial arrangement of scenarios, using four patterns of mean changes over time and four strategies for deleting data to generate subject dropout via an MAR mechanism. In data with no dropout, estimates of Δ and SE_Δ from MMRM and LOCF were identical. In data with dropout, the Type I error rates (averaged across all scenarios) for MMRM and LOCF were 5.49% and 16.76%, respectively. In 11 of the 16 scenarios, the Type I error rate from MMRM was at least 1.00% closer to the expected rate of 5.00% than the corresponding rate from LOCF. In no scenario did LOCF yield a Type I error rate that was at least 1.00% closer to the expected rate than the corresponding rate from MMRM. The average estimate of SE_Δ from MMRM was greater in data with dropout than in complete data, whereas the average estimate of SE_Δ from LOCF was smaller in data with dropout than in complete data, suggesting that standard errors from MMRM better reflected the uncertainty in the data. The results from this investigation support those from previous studies, which found that MMRM provided reasonable control of Type I error even in the presence of MNAR missingness. No universally best approach to analysis of longitudinal data exists. However, likelihood‐based MAR approaches have been shown to perform well in a variety of situations and are a sensible alternative to the LOCF approach. MNAR methods can be used within a sensitivity analysis framework to test the potential presence and impact of MNAR data, thereby assessing robustness of results from an MAR method. Copyright © 2004 John Wiley & Sons, Ltd.     

吾有志在丘壑--论辛弃疾的园林审美意识和人生态度

辛弃疾起义南归之后,与山水园林结下了不解之缘,他游览过许多湖山胜景,建造了自己的第宅园林,并创作了大量的与山水园林有关的词篇.他以多彩的笔墨描绘了自然山水和庭园风光,表现出崇尚自然、虚淡的审美意识,并在一定程度上抒写了随遇而安、超然放旷的人生态度.     

小说的生命叙事与人的生命建构

生命叙事把对人类肉身生存境况的关怀逐步推进到类似宗教境界的精神追求；它描述生命从物质到精神的孕育、产生、冲突、升腾的变化过程，是在对生命现实反思基础上的想像和升华。生命叙事的起点及归宿都是对蓬勃的生命状态的渴望和追求，它把叩问人类心灵的意义、建构理想的生命作为自己的神圣使命。     

近代资本主义生产生活方式对中国传统慈善事业的影响——以北京为例

以交通、通讯、新闻舆论等为典型代表的近代西方资本主义生产与生活方式传入中国后，它们或便利救济物资的调配，或加速救助对象的区域流动，或监督与制约救济事务的运转，或宣传与流播新型慈善思想等，从整体上对中国传统慈善活动的近代转型发挥强大的刺激与推动作用。     

论英语语言课程设计中的需求分析

界定需求要从目标和目的两个方面进行,这两个方面是我们发展测试、材料、教学活动、评价策略的基础。因此需求分析是语言课程建设不可分割的一部分。本文重点介绍了英语语言课程设计中需求分析的方法及步骤。目的在于强调需求分析的重要性,以及需求分析对于教师改进教学方法、提高教学效果、提高学生学习的主动性和积极性的重要意义。     

Non-ignorable missing covariate data in survival analysis: a case-study of an International Breast Cancer Study Group trial

Summary.  Non-ignorable missing data, a serious problem in both clinical trials and observational studies, can lead to biased inferences. Quality-of-life measures have become increasingly popular in clinical trials. However, these measures are often incompletely observed, and investigators may suspect that missing quality-of-life data are likely to be non-ignorable. Although several recent references have addressed missing covariates in survival analysis, they all required the assumption that missingness is at random or that all covariates are discrete. We present a method for estimating the parameters in the Cox proportional hazards model when missing covariates may be non-ignorable and continuous or discrete. Our method is useful in reducing the bias and improving efficiency in the presence of missing data. The methodology clearly specifies assumptions about the missing data mechanism and, through sensitivity analysis, helps investigators to understand the potential effect of missing data on study results.     

关于建立“成都学”的思考

通过一个城市的历史,去透视整个人类文明发展的进程、值得趋避的经验与教训,是城市学研究的根本目的.把具有两千多年历史的成都作为一个聚焦点,可以涉猎城市规模、城市生态系统、社会结构和社会文化,以及地理、历史、人才、经济、技术,城市管理机制、生态机制、监督机制和应变机制等诸多问题,这也都是当今世界性"城市化"浪潮中人们普遍关心的话题.     

爱的憧憬与“好色”情调——由川端康成孤儿的情感说起

少女光洁的肌肤、纯洁的心灵和母性的温情是孤儿川端的“救世主”,在感官与纯洁、母性与少女之间川端作品中出现了美女与佛的结合,进而形成了其文学中感官因圣洁而得到净化的“好色”情调。因此,从内在的形成原因来看,川端文学的“好色”情调是其诗化了的孤儿的缺失体验。     

The potential of integrated modelling in conservation biology: A case study of the black‐footed albatross (Phoebastria nigripes)

Conservation biology aims at assessing the status of a population, based on information which is often incomplete. Integrated population modelling based on state‐space models appears to be a powerful and relevant way of combining into a single likelihood several types of information such as capture‐recapture data and population surveys. In this paper, the authors describe the principles of integrated population modelling and they evaluate its performance for conservation biology based on a case study, that of the black‐footed albatross, a northern Pacific albatross species suspected to be impacted by longline fishing     

回归生活世界:当代道德教育的呼唤

道德教育根源于生活,旨在导引并成就一种可能的幸福生活。现实中,道德教育与生活世界的背离使回归生活成为教育界日益强烈的呼声。胡塞尔的生活世界理论为道德教育回归生活提供了理论基石,而道德教育自身与生活世界相融的特性也使其回归成为可能。