Inferences from biased samples with a memory effect

Biased sampling occurs often in observational studies. With one biased sample, the problem of nonparametrically estimating both a target density function and a selection bias function is unidentifiable. This paper studies the nonparametric estimation problem when there are two biased samples that have some overlapping observations (i.e. recaptures) from a finite population. Since an intelligent subject sampled previously may experience a memory effect if sampled again, two general 2-stage models that incorporate both a selection bias and a possible memory effect are proposed. Nonparametric estimators of the target density, selection bias, and memory functions, as well as the population size are developed. Asymptotic properties of these estimators are studied and confidence bands for the selection function and memory function are provided. Our procedures are compared with those ignoring the memory effect or the selection bias in finite sample situations. A nonparametric model selection procedure is also given for choosing a model from the two 2-stage models and a mixture of these two models. Our procedures work well with or without a memory effect, and with or without a selection bias. The paper concludes with an application to a real survey data set.     

André Dabrowski's work on limit theorems and weak dependence

André Robert Dabrowski, Professor of Mathematics and Dean of the Faculty of Sciences at the University of Ottawa, died October 7, 2006, after a short battle with cancer. The author of the present paper, a long‐term friend and collaborator of André Dabrowski, gives a survey of André's work on weak dependence and limit theorems in probability theory. The Canadian Journal of Statistics 37: 307–326; 2009 © 2009 Statistical Society of Canada     

New aspects of Bregman divergence in regression and classification with parametric and nonparametric estimation

In statistical learning, regression and classification concern different types of the output variables, and the predictive accuracy is quantified by different loss functions. This article explores new aspects of Bregman divergence (BD), a notion which unifies nearly all of the commonly used loss functions in regression and classification. The authors investigate the duality between BD and its generating function. They further establish, under the framework of BD, asymptotic consistency and normality of parametric and nonparametric regression estimators, derive the lower bound of their asymptotic covariance matrices, and demonstrate the role that parametric and nonparametric regression estimation play in the performance of classification procedures and related machine learning techniques. These theoretical results and new numerical evidence show that the choice of loss function affects estimation procedures, whereas has an asymptotically relatively negligible impact on classification performance. Applications of BD to statistical model building and selection with non‐Gaussian responses are also illustrated. The Canadian Journal of Statistics 37: 119‐139; 2009 © 2009 Statistical Society of Canada     

Local linear fitting and improved estimation near peaks

The authors look into the problem of estimating regression functions that exhibit jump irregularities in the first derivative. They investigate the behaviour of the bias in the local linear fit and show the superior performance of appropriate one‐sided versions of the local linear fit near such irregularities. They then propose an improved estimation procedure based on data‐driven selection of a conventional or one‐sided local linear fit according to a residual sum of squares type of criterion. The authors provide theoretical results and illustrate the method both on simulated and real‐life data examples. The Canadian Journal of Statistics 37: 453–475; 2009 © 2009 Statistical Society of Canada     

基于G3指南的河北省煤矿企业社会责任评价体系的构建

评价一个煤矿企业履行社会责任好坏,需要有一套相对公平合理的评价体系.全球报告倡议组织发布的G3指南为建立煤矿企业社会责任体系提供了方向.本文对河北省煤矿企业社会责任现状进行了分析,指出基于G3指南的煤矿企业社会责任评价体系的构建还应考虑河北煤矿行业的特殊性,应建立员工、安全、经济、环境、社会五位一体的企业社会责任评价体系.     

完善社会主义市场经济体制进程中的行政管理体制改革

文章根据党的十六大报告、十六届三中全会《决定》和四中全会《决定》的精神,论述了在完善社会主义市场经济体制进程中如何进行行政管理体制改革的问题。主要内容是:进一步转变观念;进一步转变政府经济管理职能;进一步调整机构设置,理顺部门职责分工;推进政府各项配套改革;深化地方行政管理体制改革;合理划分中央和地方经济社会事务的管理责权。     

多媒体网络下的生物教学

生物学是研究生物的形态、结构、生物分类、遗传和变异、进化、生态的科学。生物学的教学注重于宏观和微观两个方面,强调实验能力和科学素质的培养。而多媒体可以化静为动,以虚为实,化抽象为直观,能够拓宽课本知识体系,拓宽教学的时间和空间,拓宽和加深课堂学习的内涵和外延。