Collective versus Individual Effects in Survival Analysis of Multiple Failures

In survival analysis, we sometimes encounter data with multiple censored outcomes. Under certain scenarios, partial or even all covariates have ‘similar’ relative risks on the multiple outcomes in the Cox regression analysis. The similarity in covariate effects can be quantified using the proportionality of regression coefficients. Identifying the proportionality structure, or equivalently whether covariates have individual or collective effects, may have important scientific implications. In addition, it can lead to a smaller set of unknown parameters, which in turn results in more accurate estimation. In this article, we develop a novel approach for identifying the proportionality structure. Simulation shows the satisfactory performance of the proposed approach and its advantage over estimation under no assumed structure. We analyse three datasets to demonstrate the practical application of the proposed approach.     

Unified multivariate survival model with a surviving fraction: an application to a Brazilian customer churn data

In this paper we propose a new lifetime model for multivariate survival data in presence of surviving fractions and examine some of its properties. Its genesis is based on situations in which there are m types of unobservable competing causes, where each cause is related to a time of occurrence of an event of interest. Our model is a multivariate extension of the univariate survival cure rate model proposed by Rodrigues et al. [37 J. Rodrigues, V.G. Cancho, M. de Castro, and F. Louzada-Neto, On the unification of long-term survival models, Statist. Probab. Lett. 79 (2009), pp. 753–759. doi: 10.1016/j.spl.2008.10.029[Crossref], [Web of Science ®] , [Google Scholar]]. The inferential approach exploits the maximum likelihood tools. We perform a simulation study in order to verify the asymptotic properties of the maximum likelihood estimators. The simulation study also focus on size and power of the likelihood ratio test. The methodology is illustrated on a real data set on customer churn data.     

Influence diagnostics for the Weibull-Negative-Binomial regression model with cure rate under latent failure causes

In this paper, we propose a flexible cure rate survival model by assuming that the number of competing causes of the event of interest follows the Negative Binomial distribution and the time to event follows a Weibull distribution. Indeed, we introduce the Weibull-Negative-Binomial (WNB) distribution, which can be used in order to model survival data when the hazard rate function is increasing, decreasing and some non-monotonous shaped. Another advantage of the proposed model is that it has some distributions commonly used in lifetime analysis as particular cases. Moreover, the proposed model includes as special cases some of the well-know cure rate models discussed in the literature. We consider a frequentist analysis for parameter estimation of a WNB model with cure rate. Then, we derive the appropriate matrices for assessing local influence on the parameter estimates under different perturbation schemes and present some ways to perform global influence analysis. Finally, the methodology is illustrated on a medical data.     

试论司马光的经济思想

司马光的经济思想是保守的,但他的保守是建立在他对中华帝国深刻理解的基础上的。他主张开源节流,阐扬轻徭薄赋、黜奢崇俭、蓄积与常平的“富民”思想。针对日益严重的财政经济危机,他提出了一整套经济改革的主张。最主要的是他对传统社会经济运行规律和经济管理的深刻体认。     

Graphical representation of survival curves in the presence of time-dependent categorical covariates with application to liver transplantation

Graphical representation of survival curves is often used to illustrate associations between exposures and time-to-event outcomes. However, when exposures are time-dependent, calculation of survival probabilities is not straightforward. Our aim was to develop a method to estimate time-dependent survival probabilities and represent them graphically. Cox models with time-dependent indicators to represent state changes were fitted, and survival probabilities were plotted using pre-specified times of state changes. Time-varying hazard ratios for the state change were also explored. The method was applied to data from the Adult-to-Adult Living Donor Liver Transplantation Cohort Study (A2ALL). Survival curves showing a ‘split’ at a pre-specified time t allow for the qualitative comparison of survival probabilities between patients with similar baseline covariates who do and do not experience a state change at time t. Time since state change interactions can be visually represented to reflect changing hazard ratios over time. A2ALL study results showed differences in survival probabilities among those who did not receive a transplant, received a living donor transplant, and received a deceased donor transplant. These graphical representations of survival curves with time-dependent indicators improve upon previous methods and allow for clinically meaningful interpretation.     

反贪侦查中非法证据排除规则的现实应对

新刑事诉讼法在总结实践经验的基础上进一步规范和完善了我国非法证据排除规则。该规则的确立和应用将对反贪侦查工作带来巨大的影响和挑战,也将对办案人员的素质提出更高的要求。要保障反贪侦查工作依法、持续、健康开展,就必须对非法证据排除规则进行理智辩证的对待、认真细致的研究和积极主动的应对。以章国锡受贿案为透视,提出了在反贪侦查工作中,严格执行收集证据的禁止性规定,全面落实全程同步录音录像制度,提高侦查人员出庭作证的应对能力,建立非法证据排除的预警机制和做好证据的事后补正等应对非法证据排除规则之对策。     

论创新型高校组织文化特征

面向21世纪的高等教育改革实践中,突出加强大学生创新知识的传授、创新能力和创新素质的培养,以造就适应知识经济时代和我国社会主义建设事业需要的创新型高级专业人才,无疑是一项十分紧迫的任务。我们比以往任何时候更坚信国家真正的财富是人民的素质,高校组织文化对开展全面创新素质教育起到了至关重要的作用。对创新型高校组织文化特征的浅析将会为高校进行全面素质教育提供一种新的思路。     

在现实主义和现代主义的视野里寻求和谐生存之道——论D·H·劳伦斯的《儿子与情人》

D.H.劳伦斯在小说《儿子与情人》中,通过批判现实主义手法描述了主人公保罗的爱情悲剧和家庭悲剧,揭示了英国工业文明对自然环境及人类和谐生存状态的破坏。同时,作为一个现代主义作家,劳伦斯探索了人的潜意识及如何在现代文明中构建和谐生存之道。劳伦斯认为,人类只有与自然界保持和谐的关系、重建两性之间和谐、自然的关系,才能克服现代文明社会带来的弊端,实现生存状态的和谐。劳伦斯对人类生存困境的探索不仅为同时代人提供了获得救赎的全新思路,在当今呼唤和谐社会的时代,仍为我们提供了有益的借鉴。     

《无名的裘德》中的主题悖论

《无名的裘德》是一部杰出的现实主义作品,是哈代“性格与环境”小说中极为成功的一部。小说通过“主题对立”这一艺术手法深刻地揭示了人性,暴露了人类社会中许多错综复杂的关系,揭示了人类生存与存在中的一系列悖论,显示出极大的反讽效果。     

新规则对湖南省第八届大学生运动会武术比赛的影响

运用采献资料法,临场统计法和数理统计法对湖南省第八届大学生运动会武术比赛中使用的新规则做了研究,其中动作质量、演练水平和难度得分对最后的成绩影响大相径庭,对金牌分布的影响是显而易见的,通过研究分析,最后提出了相关建议,旨在为湖南省高校武术训练提供理论和实践依据。