Empirical Analysis of Interval-Censored Failure Time Data with Linear Transformation Models

Interval-censored data naturally arise in many studies. For their regression analysis, many approaches have been proposed under various models and for most of them, the inference is carried out based on the asymptotic normality. In particular, Zhang et al. (2005) discussed the procedure under the linear transformation model. It is well-known that the symmetric property implied by the normal distribution may not be appropriate sometimes. Also the method could underestimate the variance of estimated parameters. This paper proposes an empirical likelihood-based procedure for the problem. Simulation and the analysis of a real data set are conducted to assess the performance of the procedure.     

A Multiple Imputation Approach to the Analysis of Current Status Data with the Additive Hazards Model

This article discusses regression analysis of current status data, which occur in many fields including cross-sectional studies, demographical investigations, and tumorigenicity experiments (Keiding, 1991 Keiding , N. ( 1991 ). Age-specific incidence and prevalence: a statistical perspective (with discussion) . J. Roy. Statist. Soc. Ser. A 154 : 371 – 412 .[Crossref] , [Google Scholar]; Sun 2006 Sun , J. ( 2006 ). The Statistical Analysis of Interval-Censored Failure Time Data . New York : Springer-Verlag . [Google Scholar]). For the problem, we focus on the situation where the survival time of interest can be described by the additive hazards model and a multiple imputation approach is presented for inference. A major advantage of the approach is its simplicity and it can be easily implemented by using the existing software packages for right-censored failure time data. Extensive simulation studies are conducted and indicate that the approach performs well for practical situations and is comparable to the existing methods. The methodology is applied to a set of current status data arising from a tumorigenicity experiment and the model checking is discussed.     

Nonparametric Tests for Stratum Effects in the Cox Model

Thispaper considers the stratified proportional hazards model witha focus on the assessment of stratum effects. The assessmentof such effects is often of interest, for example, in clinicaltrials. In this case, two relevant tests are the test of stratuminteraction with covariates and the test of stratum interactionwith baseline hazard functions. For the test of stratum interactionwith covariates, one can use the partial likelihood method (Kalbfleischand Prentice, 1980; Lin, 1994). For the test of stratum interactionwith baseline hazard functions, however, there seems to be noformal test available. We consider this problem and propose aclass of nonparametric tests. The asymptotic distributions ofthe tests are derived using the martingale theory. The proposedtests can also be used for survival comparisons which need tobe adjusted for covariate effects. The method is illustratedwith data from a lung cancer clinical trial.     

Designing and integrating composite networks for monitoring multivariate gaussian pollution fields

Networks of ambient monitoring stations are used to monitor environmental pollution fields such as those for acid rain and air pollution. Such stations provide regular measurements of pollutant concentrations. The networks are established for a variety of purposes at various times so often several stations measuring different subsets of pollutant concentrations can be found in compact geographical regions. The problem of statistically combining these disparate information sources into a single 'network' then arises. Capitalizing on the efficiencies so achieved can then lead to the secondary problem of extending this network. The subject of this paper is a set of 31 air pollution monitoring stations in southern Ontario. Each of these regularly measures a particular subset of ionic sulphate, sulphite, nitrite and ozone. However, this subset varies from station to station. For example only two stations measure all four. Some measure just one. We describe a Bayesian framework for integrating the measurements of these stations to yield a spatial predictive distribution for unmonitored sites and unmeasured concentrations at existing stations. Furthermore we show how this network can be extended by using an entropy maximization criterion. The methods assume that the multivariate response field being measured has a joint Gaussian distribution conditional on its mean and covariance function. A conjugate prior is used for these parameters, some of its hyperparameters being fitted empirically.     

Fitting competing risks data to bivariate Pareto models

This paper revisits two bivariate Pareto models for fitting competing risks data. The first model is the Frank copula model, and the second one is a bivariate Pareto model introduced by Sankaran and Nair (1993 Sankaran, P. G., and N. U. Nair. 1993. A bivariate Pareto model and its applications to reliability. Naval Research Logistics 40 (7):1013–1020. doi:10.1002/1520-6750(199312)40:7%3c1013::AID-NAV3220400711%3e3.0.CO;2-7.[Crossref], [Web of Science ®] , [Google Scholar]). We discuss the identifiability issues of these models and develop the maximum likelihood estimation procedures including their computational algorithms and model-diagnostic procedures. Simulations are conducted to examine the performance of the maximum likelihood estimation. Real data are analyzed for illustration.     

审议制在欧盟食品安全监管中的运用

对于国务院的改革，杜钢建教授提出了专家参与的审议制。但是从理论到实践，我们需要考虑的是对于这个由杜钢建教授提出的政府内部专家、专业领域专家和代表民意专家参与的审议制该如何制度化，又该如何在实践中运用。对此，欧盟食品安全监管中的专家参与给我们提供了可资借鉴的经验，尤其是在疯牛病危机中它所经历的教训和由此进行的改革更是值得我们参考。     

试论在西夏的藏传佛教僧人及其地位、作用

12-13世纪初,藏传佛教噶举派、萨迦派僧人纷纷到西夏传法,使藏传佛教当时流行的主要密法传播到西夏并形成一定规模。西夏政府亦对藏传佛教显示出极高的热情,给予吐蕃僧人以很高的待遇,并在法律上享有诸多特权。藏传佛教僧人在西夏除了传法译经外,还在政府机构中担任职务、在外交活动中充当使臣等,对加强吐蕃民族与西夏境内各民族间的相互了解和联系有着积极的意义。     

高梁──苏丹草杂交种干物质积累分配及光合性能的研究

研究表量，高粱—苏丹草杂交种的单株生物量高，其干物质积累量高于甜高粱杂交种和粒用高粱杂交种．各器官的干物质积累量以分蘖茎为最高．并且增长迅速．主茎和分蘖茎的干物质分配率在生育后期无负值．高粱—苏丹草杂交种获得较高生物量的原因是分蘖性强，致使产生较高的ＬＡＩ和ＣＧＲ．     

异质性视角下中国农村居民减贫效应研究——基于FGT贫困指数的分解新方法

在我国即将完成脱贫攻坚背景下,异质性在居民减贫并防返贫进程中逐渐起到关键作用。本文通过反事实分析法将收入分布变迁分解为均值、方差以及残差三种变化,进而将其引入贫困分解中,对我国农村及区域贫困进行分解。研究表明,引入收入分布变迁贫困分解结果具有稳健性,且农村居民收入增长效应与离散效应存在非对称性,提高收入已不足以弥补收入差距扩大带来的贫困加深效应,而异质效应和离散效应间存在对称性,居民异质性在减贫进程中逐渐起到关键作用。同时从区域视角看,东部区域异质效应减贫效果明显高于增长效应;中部区域增长效应和异质效应均具有显著减贫效果;而西南区域增长效应的减贫效果最显著。     

A qualitative case study of a Korean former addict’s existential self‐interpretation and identity transformation

This study explored the case of a former addict, focusing on his existential self‐interpretation and identity transformation process. This study began from the question of whether philosophical processes related to existential self‐interpretation could lead to the formation of the concept of bottoming out and of identity transformation. To answer this question, the study analyzed the case of a male in his mid‐forties who was addicted to drugs for approximately 30 years and has only recently maintained abstinence. The study used the phenomenological approach to determine the meaning drugs held for him in each stage, and what drug‐related identity he had in each stage. Further, this study identified the integrative implications of these meanings in terms of existential self‐interpretation and identity transformation. The four different identities the man identified for the four stages of his life were juvenile delinquent, gang member, half‐gangster, and breadwinner, and the associated meanings drugs had for him during each period were “glue,” “filthy,” “leeches,” and “abstinence,” respectively. Finally, this study elucidated the integration of these meanings through the hermeneutic circle, identified the social welfare implications of the findings, and developed educational recommendations.