A tutorial on rank-based coefficient estimation for censored data in small- and large-scale problems

The analysis of survival endpoints subject to right-censoring is an important research area in statistics, particularly among econometricians and biostatisticians. The two most popular semiparametric models are the proportional hazards model and the accelerated failure time (AFT) model. Rank-based estimation in the AFT model is computationally challenging due to optimization of a non-smooth loss function. Previous work has shown that rank-based estimators may be written as solutions to linear programming (LP) problems. However, the size of the LP problem is O(n ²+p) subject to n ² linear constraints, where n denotes sample size and p denotes the dimension of parameters. As n and/or p increases, the feasibility of such solution in practice becomes questionable. Among data mining and statistical learning enthusiasts, there is interest in extending ordinary regression coefficient estimators for low-dimensions into high-dimensional data mining tools through regularization. Applying this recipe to rank-based coefficient estimators leads to formidable optimization problems which may be avoided through smooth approximations to non-smooth functions. We review smooth approximations and quasi-Newton methods for rank-based estimation in AFT models. The computational cost of our method is substantially smaller than the corresponding LP problem and can be applied to small- or large-scale problems similarly. The algorithm described here allows one to couple rank-based estimation for censored data with virtually any regularization and is exemplified through four case studies.     

Correlation Coefficient Revisited

Elementary approaches to prove basic properties of the correlation coefficient are of pedagogical interest. Besides posing another proof, this article gives variations of the proofs already existing in the statistical literature     

Multiplicative Adjustment Method for Semiparametric Regression with Mixing Dependent Data

In this article, we extend a semiparametric regression estimator with multiplicative adjustment to time series context. The asymptotic theory and results from a simulation study are discussed. Theoretical results and numerical comparison show that, in the time series case, the semiparametric estimator is better than the traditional local polynomial estimator in a wide neighbourhood around the true regression function.     

Approximating discrete multivariate distributions prom known moments

To approximate the joint distribution of the two-colony stepping-stone model, a finite mixture approach is proposed for constructing discrete multi-variate distributions. This approach generahzes the classic method of linear combinations of independent variables. The stepping-stone model is approximated through matching known moments. Numerical examples from entomology are given. Comparisons are made with the work by Wehrly et al (1993).     

大股东控制影响公司现金持有量的实证分析

 本文结合我国上市公司所面临的内部治理机制特点及外部治理环境,从大股东行为的视角对公司现金持有量的影响因素进行实证分析。在加入年度控制变量、行业控制变量和公司财务特征控制变量后,对三项反映大股东行为特征的因素,即大股东持股比例、大股东属性和制度环境因素对公司现金持有量的影响进行了检验。结果表明,第一大股东持股比例较高的公司持有较多的现金,大股东的高持股比例是其占用企业资金侵占中小股东利益的基础。与国有企业相比,民营企业因遭受较强的外部融资约束而持有较高水平的现金。此外,制度环境的发展程度与公司现金持有水平正相关,表明制度环境较好地区的公司持有较多的现金。     

移动支付使用者使用意向与使用行为模型及实证研究

为了了解影响移动支付使用者使用意向与实际使用的因素,对基于整合型信息接受模型的新增成本影响因素进行验证性因子分析.结果显示:移动支付使用成本对移动支付使用意愿有着最显著的影响,社会影响、努力期望和期望效用对移动支付使用意愿具有显著的正向影响;移动支付使用意愿和便利条件对使用行为有着非常显著的积极影响.     

打破传统模式 培养创新人才--"高师美术教育专业水彩画符号、图式建构教学的研究与实践"总结

高师美术教育专业培养模式与培养具有创新性的新型城乡中学美术教师的宗旨相背已久.从基础水彩画课入手进行符号、图式建构教学的研究与实践,有利于该专业课程体系改革的全面实施,进而打破传统培养模式,为城乡中学输送具有审美能力、创新能力的新型人才.     

地方政府权力清单制度法治化研究

地方政府权力清单制度的法治化是通过法律规范地方各级政府及其部门的权力以清单的形式详细清晰地予以公布,并产生强制性的约束力,规范政府的权力边界,要求政府必须按照清单所列权力依法行政,不允许越权执法,旨在制约行政权力,保障公民权利。本文基于行政法定原则、行政公开原则、行政便民原则阐释了地方政府权力清单制度法治化的理论基础,然而,地方政府权力清单制度的实践中仍存在一些问题,应当从权力类型的科学化管理和权力清单范围全覆盖等方面优化权力清单的内容,从权力清单制定主体、权力行使的程序和清单制度的实施方式等方面提供程序性的保障,从权力清单的责任约束和有效监督方面建立刚性制约机制,以此来完善地方政府权力清单制度的法治化,防止行政权力的滥用,推进法治政府的建设。     

基于构建现代产业体系的河北省人力资本集聚研究

人力资本是优化产业结构的核心驱动要素,而人力资本的集聚是构建河北省现代产业体系的重要前提。文章以人力资本的集聚对河北省构建现代产业体系的影响为背景,对河北省人力资本集聚影响因素进行研究,在实证分析的基础上,探索构建河北省现代产业体系过程中的人力资本集聚路径。