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.     

Statistical and Combinatorial Aspects of Comparative Genomics*

Abstract. This document presents a survey of the statistical and combinatorial aspects of four areas of comparative genomics: gene order based measures of evolutionary distances between species, construction of phylogenetic trees, detection of horizontal transfer of genes, and detection of ancient whole genome duplications.     

On Optimality of Bayesian Wavelet Estimators

Abstract.  We investigate the asymptotic optimality of several Bayesian wavelet estimators, namely, posterior mean, posterior median and Bayes Factor, where the prior imposed on wavelet coefficients is a mixture of a mass function at zero and a Gaussian density. We show that in terms of the mean squared error, for the properly chosen hyperparameters of the prior, all the three resulting Bayesian wavelet estimators achieve optimal minimax rates within any prescribed Besov space     for p  ≥ 2. For 1 ≤  p  < 2, the Bayes Factor is still optimal for (2 s +2)/(2 s +1) ≤  p  < 2 and always outperforms the posterior mean and the posterior median that can achieve only the best possible rates for linear estimators in this case.     

Assessing goodness-of-fit of categorical regression models based on case-control data

Demonstrated equivalence between a categorical regression model based on case‐control data and an I‐sample semiparametric selection bias model leads to a new goodness‐of‐fit test. The proposed test statistic is an extension of an existing Kolmogorov–Smirnov‐type statistic and is the weighted average of the absolute differences between two estimated distribution functions in each response category. The paper establishes an optimal property for the maximum semiparametric likelihood estimator of the parameters in the I‐sample semiparametric selection bias model. It also presents a bootstrap procedure, some simulation results and an analysis of two real datasets.     

相互依存型外交战略：“入世”后我国外交战略的理性选择

我国的外交是为现代化建设服务的.在由于经济全球化使各国日益增强相互依存关系的背景下,尤其是我国加入世贸组织后,实行相互依存型发展外交战略是一种理性选择.这种通过多边对话、协调平衡和合作的途径,以发展求和平,促进我国经济发展的外交战略的调整和实行,有它的必然性与可行性.     

绿色供应链管理动力/压力影响模型实证研究

文章借鉴国外文献及国内环保专家的意见设计问卷进行调研,通过因子分析识别出中国制造企业绿色供应链管理的压力/动力和实践的主要因子.对因子进行相关分析和回归分析,根据数据结合国内外相关情况探讨动力/压力是如何影响绿色供应链管理实践,提出中国制造企业绿色供应链管理的动力/压力影响模型.     

统计执法的博弈分析

针对目前中国统计数据失真相当严重并引起社会各界普遍关注的现象，运用博弈论作为分析工具，引入重复博弈研究了统计执法中数据报方与查方的利益冲突关系，从统计执法的角度揭示了统计数据失真的主要原因，并提出了相应的五项对策。     

中国医疗机构定价中的问题及对策建议

医疗机构医疗服务定价需要考虑因素是医疗卫生行业管理的一个重要内容,合理有效定价对实现社会公平和福利分配,保障居民生命健康、促进社会稳定的具有重要的现实意义。本文对国内外医疗定价的几种主要模式进行简要介绍,然后分析一下我国现行医疗服务定价存在问题的原因,并给出几点改革建议,讨论需要建立一个合理的定价体系和监管体系需要考虑因素。     

传统科技视野下的恐怖主义及其应对

科学技术的发展及其被恶意运用,使当代的恐怖主义活动变得更加复杂多样和令人恐慌.掌握和使用高科技的超级恐怖主义组织的确存在,但对于一般恐怖分子而言,高科技的运用还不大现实.多数情况下,都是传统通用科技引导着普通的恐怖主义活动.恐怖活动与传统通用科技相伴发展的历史事实,表明传统通用科技对恐怖主义与反击恐怖主义双重力量扩张所起的作用,具体体现在武器技术、交通运输和通信技术的应用等方面.科学技术既是恐怖主义盛行的因素,也是恐怖主义的克星,运用高科技手段反击恐怖主义也是我们的必然选择.     

经贸院系英语教学模式探讨

分析目前我国英语教学与研究的误区。提出经贸院系学生应达到的英语水平目标；探讨经贸院系英语教学可采取六种教学模式。