A new alternative to the standard F test for clustered data

The data collection process and the inherent population structure are the main causes for clustered data. The observations in a given cluster are correlated, and the magnitude of such correlation is often measured by the intra-cluster correlation coefficient. The intra-cluster correlation can lead to an inflated size of the standard F test in a linear model. In this paper, we propose a solution to this problem. Unlike previous adjustments, our method does not require estimation of the intra-class correlation, which is problematic especially when the number of clusters is small. Our simulation results show that the new method outperforms the existing methods.     

Confidence interval estimation of the difference between paired AUCs based on combined biomarkers

In many diagnostic studies, multiple diagnostic tests are performed on each subject or multiple disease markers are available. Commonly, the information should be combined to improve the diagnostic accuracy. We consider the problem of comparing the discriminatory abilities between two groups of biomarkers. Specifically, this article focuses on confidence interval estimation of the difference between paired AUCs based on optimally combined markers under the assumption of multivariate normality. Simulation studies demonstrate that the proposed generalized variable approach provides confidence intervals with satisfying coverage probabilities at finite sample sizes. The proposed method can also easily provide P-values for hypothesis testing. Application to analysis of a subset of data from a study on coronary heart disease illustrates the utility of the method in practice.     

Least squares estimation of varying‐coefficient hazard regression with application to breast cancer dose‐intensity data

To enhance modeling flexibility, the authors propose a nonparametric hazard regression model, for which the ordinary and weighted least squares estimation and inference procedures are studied. The proposed model does not assume any parametric specifications on the covariate effects, which is suitable for exploring the nonlinear interactions between covariates, time and some exposure variable. The authors propose the local ordinary and weighted least squares estimators for the varying‐coefficient functions and establish the corresponding asymptotic normality properties. Simulation studies are conducted to empirically examine the finite‐sample performance of the new methods, and a real data example from a recent breast cancer study is used as an illustration. The Canadian Journal of Statistics 37: 659–674; 2009 © 2009 Statistical Society of Canada     

Estimation of Distribution Functions Using Data from Different Environments

Suppose that when a unit operatesin a certain environment, its lifetime has distribution G,and when the unit operates in another environment, its lifetimehas a different distribution, say F. Moreover, supposethe unit is operated for a certain period of time in the firstenvironment and is then transferred to the second environment.Thus we observe a censored lifetime in the first environmentand a failure time of a ``used' unit in the second environment.We propose an EM algorithm approach for obtaining a self-consistentestimator of F. Moreover, suppose using observations from both environments.The case where failure times are subject to right censoring isconsidered as well. We also establish the maximum likelihoodestimator of F. Moreover, suppose when the unit is repairable. Applicationand simulation studies are presented to illustrate the methodsderived.     

Dependence Estimation Over a Finite Bivariate Failure Time Region

This articleconcerns nonparametric estimation of association between bivariatefailure times. In the presence of independent right censoring,the support for failure time variates may be restricted and measuresof dependence over a finite failure time region may be of particularinterest. To this end, the reciprocal cross ratio function, weightedby the bivariate failure time density, is proposed as a summarymeasure of dependence over a failure time region. This `relativerisk' estimator is shown to be consistent and asymptoticallynormally distributed, with consistent bootstrap variance estimator.A finite-region version of Kendall's tau, which is suitable forcensored failure time data, is also proposed, and correspondingasymptotic distribution theory is noted. The accuracy of theseasymptotic approximations is studied in simulations and an illustrationis provided.     

试论戏曲脸谱的意象营构与表情体验

戏曲脸谱是以高度夸张、高度抽象等艺术手段体现的意象创造。艺术家在舞台表演过程中 ,完成了发于内、形于外的充满情感的表情审美体验。脸谱的意象营构正是在表情体验指导下 ,将所获得的审美理想付诸艺术创造的具体实践。从无形到有形 ,是脸谱意象营构的艺术规律 ,它把艺术家的审美体验变为可以具体感知的艺术形象。脸谱的意象营构遵循“经营位置”的形式美法则 ,赋予脸谱意象以生动的感性表现形式。脸谱的意象营构脱离客观表象 ,而以表情体验作为审美依据 ,实现了遗貌取神 ,离形得似的艺术追求 ,达到了神似的艺术境界     

简论中国古代的环境伦理思想

中国古代环境伦理思想的哲学基础是天人统一观 ,尊重生命 ,兼爱万物是这一伦理思想的主题。寡欲节用是中国古代珍惜自然资源的传统美德。中国古代就已形成了渗透环境伦理意识的政法理念。不同于西方传统伦理学所奉行的人类中心主义 ,中国先哲主张保持人和自然关系的和谐统一。作为珍贵的文化遗产 ,中国古代环境伦理思想是保证和维护中华民族几千年生存繁衍和中华文明绵延不断的重要因素之一 ,它对现代环境伦理学的发展也具有重大的理论借鉴价值。在当前现代化建设中 ,有分析地借鉴我国古代的环境伦理思想 ,对创建适合我国国情的环境伦理学 ,解决社会可持续发展问题是极有意义的     

网页制作中应注意的几个问题

本文针对目前在网页制作热潮中,制作者经常遇到的一些问题谈谈自己的几点感受,希望对学习网页制作的同仁有所帮助.     

从基于资源到面向需求——地方政府决策的一种利益分析

市场经济条件下,一些地方政府和企业、事业单位仍然基于地方资源而不是生产者和消费者通过市场交换所反映出来的需求进行决策,这已导致低效、封闭以及资源配置不合理,并加剧寻租现象。本文主要分析基于资源决策思路的负面效果、原因、表现,以及向面向需求决策方式转变的重要性。     

试论周作人的文学批评

周作人的文学地位不仅在于散文的贡献,而且在于文学批评的开展,他的文学批评具有西方近现代人文主义思想的特征,即对“人”的关注,并由此理解与持持新潮的出路的作家作品,开拓一些文学样式的新的美学风格,同时,周作人的文学批评又具有中国古典美学的特点,即以平淡自然为文学批评标准去衡量作家作品,其文学批评的风格也与中国传统的文评风格相似。