Nonparametric and semiparametric estimation of the three way receiver operating characteristic surface

In many situations the diagnostic decision is not limited to a binary choice. Binary statistical tools such as receiver operating characteristic (ROC) curve and area under the ROC curve (AUC) need to be expanded to address three-category classification problem. Previous authors have suggest various ways to model the extension of AUC but not the ROC surface. Only simple parametric approaches are proposed for modeling the ROC measure under the assumption that test results all follow normal distributions. We study the estimation methods of three-dimensional ROC surfaces with nonparametric and semiparametric estimators. Asymptotical results are provided as a basis for statistical inference. Simulation studies are performed to assess the validity of our proposed methods in finite samples. We consider an Alzheimer's disease example from a clinical study in the US as an illustration. The nonparametric and semiparametric modelling approaches for the three way ROC analysis can be readily generalized to diagnostic problems with more than three classes.     

Inference of non-centrality parameter of a truncated non-central chi-squared distribution

Non-central chi-squared distribution plays a vital role in statistical testing procedures. Estimation of the non-centrality parameter provides valuable information for the power calculation of the associated test. We are interested in the statistical inference property of the non-centrality parameter estimate based on one observation (usually a summary statistic) from a truncated chi-squared distribution. This work is motivated by the application of the flexible two-stage design in case–control studies, where the sample size needed for the second stage of a two-stage study can be determined adaptively by the results of the first stage. We first study the moment estimate for the truncated distribution and prove its existence, uniqueness, and inadmissibility and convergence properties. We then define a new class of estimates that includes the moment estimate as a special case. Among this class of estimates, we recommend to use one member that outperforms the moment estimate in a wide range of scenarios. We also present two methods for constructing confidence intervals. Simulation studies are conducted to evaluate the performance of the proposed point and interval estimates.     

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.     

我国消费、投资、净出口与经济增长

 消费、投资与出口通常并称为拉动经济增长的三驾马车,对经济增长产生重要作用。同时,经济增长也影响着它们的规模。针对这种情况,本文通过建立联立方程模型以及脉冲响应函数,对我国经济1978-2006年的历史数据进行实证分析,揭示我国改革开放以来它们之间的关系。     

关于社会主义核心价值体系理论与实践研究——以江苏省为例

本文结合江苏建设中国特色社会主义的生动实践,揭示了社会主义核心价值体系在江苏表现出的鲜明特色及丰富内涵.论文认为,突显核心价值体系的区域追求,是新的历史条件下推进江苏省思想道德建设需要着力的方向,并对如何推进思想道德建设,形成科学的社会主义核心价值体系建设格局,提出了富有建设性的对策.     

论舒亶词

舒亶是北宋词坛重要词人,然其词长期以来却被文学史"遗忘".他的词在内容与题材上深化了苏轼开创的"士大夫化"抒情道路,形式上亦显出打破诗词界域,扩大词之表现功能的努力.而他参与制造的北宋"乌台诗案",也间接影响了宋词演进的轨迹.     

《大人先生传》:阮籍矛盾、苦闷一生的写照

在写于其晚年的<大人先生传>一文中,阮籍描绘了"士君子"、"隐士"、"薪者"和"大人先生"等四种人格意象.对于这四种意象所代表的意义,历来有颇多的解释,比如,冯友兰先生在其<中国哲学史新编>中认为这四种意象,很有可能是当时社会上存在的四种观点.但笔者以为,作为其晚年的作品,阮籍在这里所做的,极有可能是对其一生的回顾、总结."士君子"、"隐士"、"薪者"三者则是代表了阮籍一生不同阶段的精神状态,"大人先生"则是阮籍的精神归宿所在.而矛盾和苦闷之情,则充满着阮籍的一生,成为他一生的基调.     

托洛茨基的重大理论贡献——纪念托洛茨基诞辰130周年

托洛茨基是早期苏共领导人,著名的马克思主义革命家,毕生致力于社会主义革命运动.然而,他的命运却是悲剧性的.历史是公正的,托洛茨基最终得到肯定,是与他的马克思主义理论建树分不开的.其中,关于社会主义革命运动的理论是最突出的.托洛茨基早期的不断革命论是其革命理论的根基,是一个关于落后国家如何建立无产阶级政权的战略构想,并经受了十月革命的检验.之后,不断革命论在实践中得以发展和完善,体现为一系列具体理论:一国不能建成社会主义革命论、政治革命论、世界革命论等,从而形成了宏观的社会主义运动完整版的不断革命理论,其实质是广义的不断革命论,是对不平衡规律的运用,是对无产阶级的自主性和国际主义精神的高扬.     

论祠堂画像的模块叙述、单元叙述与模糊性叙述——以武氏祠堂前石室(武荣祠)及相关画像为例

祠堂画像最小的叙述形式为"叙述单元",不同的"叙述单元"构成不同的"叙述模块".各叙述模块在叙事意义上既具有独立性又构成联系,形成了"同构"的叙述状态和"连续"的叙事形式,并构成祠堂画像之"叙述整体"即立体叙述空间.祠堂画像各叙述模块既是墓葬主人于叙事意义上的空间延伸,也是墓葬主人于叙事意义上的叙述延展,每一个叙述模块都象征性地表现或展示着墓葬主人具有时间意义的不同的空间存在.祠堂屋顶画像不能简单地以"天上世界"来概括,它是陆地、水中与上天的模糊叙述体.祠堂画像由不同叙述模块所构成的立体叙述空问的构图形式和叙事方式,反映了汉代特定历史时期对生命永恒追求的崇拜和信仰,是这种成熟的崇拜形式和信仰方式的视觉表现和图像再现,相同和类似的视觉表现和图像再现,还存于在汉代以"铭旌"为载体的画面构图上.