Computing the log concave NPMLE for interval censored data

In analyzing interval censored data, a non-parametric estimator is often desired due to difficulties in assessing model fits. Because of this, the non-parametric maximum likelihood estimator (NPMLE) is often the default estimator. However, the estimates for values of interest of the survival function, such as the quantiles, have very large standard errors due to the jagged form of the estimator. By forcing the estimator to be constrained to the class of log concave functions, the estimator is ensured to have a smooth survival estimate which has much better operating characteristics than the unconstrained NPMLE, without needing to specify a parametric family or smoothing parameter. In this paper, we first prove that the likelihood can be maximized under a finite set of parameters under mild conditions, although the log likelihood function is not strictly concave. We then present an efficient algorithm for computing a local maximum of the likelihood function. Using our fast new algorithm, we present evidence from simulated current status data suggesting that the rate of convergence of the log-concave estimator is faster (between \(n^{2/5}\) and \(n^{1/2}\)) than the unconstrained NPMLE (between \(n^{1/3}\) and \(n^{1/2}\)).     

特征AHP在高校教师教学质量评定中的应用

本文针对高校教师教学质量的评定提出了一种特征层次分析法。首先通过分析教学质量的影响因素,建立三层层次分析模型。在其基础上引入特征法,选取特征群并确定特征群中个体的权重,利用反算法根据组合权重及方案层权重,求取准则层评定指标权重,避免了不同质指标间对比的不确定性,摒除了专家直接给出评定指标对比矩阵的主观性,减少了对教师评定过程的不一致性和不完备性。     

Opportunities for woman-initiated HIV prevention methods among female sex workers in southern China

Rapid changes in China over the past two decades have led to significant problems associated with population migration and changing social attitudes, including a growing sex industry and concurrent increases in STIs and HIV. This article reports results of an exploratory study of microbicide acceptability and readiness and current HIV prevention efforts among female sex workers in two rural and one urban town in Hainan and Guangxi Provinces in southern China. The study focused on these women's knowledge and cultural understandings of options for protecting themselves from exposure to STIs and HIV, and the potential viability and acceptability of woman-initiated prevention methods. We report on ethnographic elicitation interviews conducted with women working within informal sex-work establishments (hotels, massage and beauty parlors, roadside restaurants, boarding houses). We discuss implications of these findings for further promotion of woman-initiated prevention methods such as microbicides and female condoms among female sex workers in China.     

20世纪20年代末京津地区外报的衰落评析

本文展现了20世纪20年代京津地区外文报纸从北洋军阀统治晚期到南京政府统一全国初期被层层挤压、无法立足的衰落过程,并对后期中国政府和中国人民打击外报的缘由、手段,以及效果进行深入分析。外报的衰落标志着中国民族报业逐步摆脱外国势力,进入一个新阶段。     

"'国家与文明起源笔记',还是'人类学笔记'"学术争鸣的重要意义

<东南学术>开展的马克思晚年笔记的学术争鸣具有重要的意义.其一,表示我国学界在马克思主义哲学方面从一般原理的研究进入到重视文本的探讨.这种文本的探讨深入到唯物史观的三个方面:一是这一历史观在唯物史观制定初期没有也无法制定的部分,这就是"国家与文明起源"的内容;二是社会发展规律与社会发展道路的关系问题;三是马克思史学研究的方法问题,这表现为逻辑方法与实证方法的关系问题.对此,争鸣双方都在各自研究的基础上有着深刻的理解.其二,双方的分歧是同我们以往在马克思主义哲学原理的层面上对唯物史观理论的理解有关系.长期以来,哲学教科书遵循的是"二分板块"结构(即辩证唯物主义与历史唯物主义),二者的关系是前者对后者是一种"推广"或"应用"的关系.今天我们关于马克思晚年笔记的争鸣,既涉及对"二分板块"观点下的唯物史观理论如何制定的理解,又与这一理论体系、历史使命或它的与时俱进的理论性和实践性有关.     

现代性与当代审美文化的结构

当代审美文化的结构性生成是在现代性进程中发生的。我们可以用“生活/艺术”、“大众/精英”、“保守/前卫”这三对范畴来描述当代审美文化的内部结构。值得注意的是,在事实性的领域中这三对范畴之间的斜线(/)不是断然明确而固定不变的,正是这条斜线的颤动、扭曲、变化甚至消失和再生,标志着当代审美文化活生生的生命存在与运动。     

Variance estimation based on blocked 3×2 cross-validation in high-dimensional linear regression

In high-dimensional linear regression, the dimension of variables is always greater than the sample size. In this situation, the traditional variance estimation technique based on ordinary least squares constantly exhibits a high bias even under sparsity assumption. One of the major reasons is the high spurious correlation between unobserved realized noise and several predictors. To alleviate this problem, a refitted cross-validation (RCV) method has been proposed in the literature. However, for a complicated model, the RCV exhibits a lower probability that the selected model includes the true model in case of finite samples. This phenomenon may easily result in a large bias of variance estimation. Thus, a model selection method based on the ranks of the frequency of occurrences in six votes from a blocked 3×2 cross-validation is proposed in this study. The proposed method has a considerably larger probability of including the true model in practice than the RCV method. The variance estimation obtained using the model selected by the proposed method also shows a lower bias and a smaller variance. Furthermore, theoretical analysis proves the asymptotic normality property of the proposed variance estimation.     

An elastic-net penalized expectile regression with applications

To perform variable selection in expectile regression, we introduce the elastic-net penalty into expectile regression and propose an elastic-net penalized expectile regression (ER-EN) model. We then adopt the semismooth Newton coordinate descent (SNCD) algorithm to solve the proposed ER-EN model in high-dimensional settings. The advantages of ER-EN model are illustrated via extensive Monte Carlo simulations. The numerical results show that the ER-EN model outperforms the elastic-net penalized least squares regression (LSR-EN), the elastic-net penalized Huber regression (HR-EN), the elastic-net penalized quantile regression (QR-EN) and conventional expectile regression (ER) in terms of variable selection and predictive ability, especially for asymmetric distributions. We also apply the ER-EN model to two real-world applications: relative location of CT slices on the axial axis and metabolism of tacrolimus (Tac) drug. Empirical results also demonstrate the superiority of the ER-EN model.     

时光·梦想

生活在19世纪的人们,乐于听到工业革命的轰鸣声。他们知道,这是“现代”的召唤。21世纪的我们,现代的我们则渴望着回到自然的怀抱。这是文明的又一道曲线。它从一个欣欣向荣滑到另一个欣欣向荣。而这两个时代都打上了进步的鲜明烙印,都同样是我们光荣的、关于自身、关于梦想的珍贵记忆。如果好奇于日常生活中的周遭事务,并执着于探求它们的来源,我们会惊奇地发现:时常光顾的超市、购物中心、度假村、俱乐部,始于世界博览会;电视机、留声机、电灯,在世博会上首次展出;甚至第一台纺织机、第一架飞机竟也是从世博会步入我们的生活。“一切始于…     

Bayesian nonparametric modelling of the link function in the single-index model using a Bernstein–Dirichlet process prior

This paper proposes the use of the Bernstein–Dirichlet process prior for a new nonparametric approach to estimating the link function in the single-index model (SIM). The Bernstein–Dirichlet process prior has so far mainly been used for nonparametric density estimation. Here we modify this approach to allow for an approximation of the unknown link function. Instead of the usual Gaussian distribution, the error term is assumed to be asymmetric Laplace distributed which increases the flexibility and robustness of the SIM. To automatically identify truly active predictors, spike-and-slab priors are used for Bayesian variable selection. Posterior computations are performed via a Metropolis-Hastings-within-Gibbs sampler using a truncation-based algorithm for stick-breaking priors. We compare the efficiency of the proposed approach with well-established techniques in an extensive simulation study and illustrate its practical performance by an application to nonparametric modelling of the power consumption in a sewage treatment plant.