Local influence in ridge semiparametric models

ABSTRACT

Ridge penalized least-squares estimators has been suggested as an alternative to the minimum penalized sum of squares estimates in the presence of collinearity among the explanatory variables in semiparametric regression models (SPRMs). This paper studies the local influence of minor perturbations on the ridge estimates in the SPRM. The diagnostics under the perturbation of ridge penalized sum of squares, response variable, explanatory variables and ridge parameter are considered. Some local influence diagnostics are given. A Monte Carlo simulation study and a real example are used to illustrate the proposed perturbations.     

Double bootstrap estimation of variance under systematic sampling with probability proportional to size

Variance estimation under systematic sampling with probability proportional to size is known to be a difficult problem. We attempt to tackle this problem by the bootstrap resampling method. It is shown that the usual way to bootstrap fails to give satisfactory variance estimates. As a remedy, we propose a double bootstrap method which is based on certain working models and involves two levels of resampling. Unlike existing methods which deal exclusively with the Horvitz–Thompson estimator, the double bootstrap method can be used to estimate the variance of any statistic. We illustrate this within the context of both mean and median estimation. Empirical results based on five natural populations are encouraging.     

Two-stage hierarchical modeling for analysis of subpopulations in conditional distributions

In this work, we develop modeling and estimation approach for the analysis of cross-sectional clustered data with multimodal conditional distributions where the main interest is in analysis of subpopulations. It is proposed to model such data in a hierarchical model with conditional distributions viewed as finite mixtures of normal components. With a large number of observations in the lowest level clusters, a two-stage estimation approach is used. In the first stage, the normal mixture parameters in each lowest level cluster are estimated using robust methods. Robust alternatives to the maximum likelihood estimation are used to provide stable results even for data with conditional distributions such that their components may not quite meet normality assumptions. Then the lowest level cluster-specific means and standard deviations are modeled in a mixed effects model in the second stage. A small simulation study was conducted to compare performance of finite normal mixture population parameter estimates based on robust and maximum likelihood estimation in stage 1. The proposed modeling approach is illustrated through the analysis of mice tendon fibril diameters data. Analyses results address genotype differences between corresponding components in the mixtures and demonstrate advantages of robust estimation in stage 1.     

从《江雪》到《寒江独钓图》--论马远山水画中的诗画融合现象

诗、画被称为姐妹艺术,在中国艺术史上,历来倾向于诗歌与绘画的融合.中国这种传统的诗画观影响着诗歌绘画的发展.马远在此影响下,用独特的艺术表现方式(水墨山水人物画)将柳宗元的诗歌<江雪>的意境很好的表达出来.文章着重探讨马远的名画<寒江独钓图>和<江雪>在意境上的融合问题,来阐述马远在南宋绘画史上对诗画走向融合的贡献.     

从冯梦龙对柳永形象的重塑看话本小说的文人化——以《众名姬春风吊柳七》对《柳耆卿诗酒玩江楼记》的改编为例

从《清平山堂话本》到“三言”,文人的参与对话本小说的发展起着至关重要的作用。以《众名姬春风吊柳七》对《柳耆卿诗酒玩江楼记》的改编为例,冯梦龙从体制、情节、语言等方面对柳永形象作了一番重塑,藉此也观见了话本小说发展史中文人化的轨迹：对话本小说体制的完善和定型化,思想主题的升华,人物形象塑造艺术的圆熟,教化性的强化,语言的雅化。     

将城市的记忆融入现代城市生活——论伊宁六星街历史街区的保护与发展策略

历史街区是城市发展的历史见证和缩影,有着深厚的文化积淀。这些悠久的历史遗迹随着时光的河流汇聚成为城市文脉,也印证着每个城市独特的风貌。本文以新疆伊宁市六星街为例,探讨在城市的发展中那些记录着时代变迁的历史街区的重要性及其保护与发展。     

北京高技术产业研发转化效率实证研究——基于随机前沿生产函数的分析

应用随机前沿生产函数模型,对北京高技术产业研发转化效率进行实证分析。研究表明,北京高技术产业研发经费的产出效率较为理想,而研发人员的产出效率存在较大的提升空间;高技术产业研发转化效率总体呈稳步上升态势,但各行业间差距明显;从影响北京高技术产业研发转化效率的因素看,产业利润和政府扶持对北京高技术产业研发转化效率都具有正向效应,市场结构对研发转化效率的影响不显著。针对上述研究结论,本文针对性提出提升北京高技术产业研发转化效率的若干建议。     

四川盆地嘉陵江组天然气藏的形成与演化研究

三叠统嘉陵江组碳酸盐岩是四川盆地内重要的产层之一。对嘉陵江组天然气组成和碳同位素特征的分析表明：嘉陵江组的天然气干燥系数大,热演化程度高,油型气和煤型气混源特征明显,但川中地区除外,主要为高熟油型气。经盆地区域构造活动和成藏要素分析,恢复了嘉陵江组天然气成藏过程,建立了川中、川东和川南地区典型构造带嘉陵江组天然气的成藏模式,发现嘉陵江组气藏均经历了古油藏—古气藏—现今气藏的漫长演化过程,与印支运动、燕山运动和喜马拉雅运动密切相关。四川盆地嘉陵江组天然气成藏遵循：高压驱动,流体跨层流动,断层裂缝疏导,膏盖油裂解气成藏的规律。