Influence diagnostics and outlier tests for semiparametric mixed models

Summary. Semiparametric mixed models are useful in biometric and econometric applications, especially for longitudinal data. Maximum penalized likelihood estimators (MPLEs) have been shown to work well by Zhang and co-workers for both linear coefficients and nonparametric functions. This paper considers the role of influence diagnostics in the MPLE by extending the case deletion and subject deletion analysis of linear models to accommodate the inclusion of a nonparametric component. We focus on influence measures for the fixed effects and provide formulae that are analogous to those for simpler models and readily computable with the MPLE algorithm. We also establish an equivalence between the case or subject deletion model and a mean shift outlier model from which we derive tests for outliers. The influence diagnostics proposed are illustrated through a longitudinal hormone study on progesterone and a simulated example.     

对网络教学的分析和探讨

随着知识经济的发展 ,网络已经日渐走入人们的生活并且开始显示其重要性。同时 ,社会对教育模式、教育手段都提出了新的要求。网络教学作为一种新型的教育方式 ,在我国迅速发展起来 ,并且成为远程教育的重要形式之一。本文就网络教学的学习理论、特点、定位以及现阶段我国网络教学与发达国家网络教学的差距进行了分析和探讨 ,并对我国网络教学今后的发展方向和需要解决的问题 ,提出了个人的见解。     

Internet与未来教育

Internet是20世纪末世界上最激动人心的发现,它将我们带入了一个完全信息化的时代,它正在改变着人们的生活和工作方式,也必将对中国未来教育发生深远的影响。从教育的内容、教育的方式方法、教育的观念等诸方面阐述了Internet对未来教育的影响,分析了未来教育将向着终身化、远程化和多媒体化、大众化、个性化、产业化和市场化等方向发展的趋势,同时提出了我们应采取的对策。     

Model diagnostics for smoothing spline ANOVA models

The author proposes some simple diagnostics for assessing the necessity of selected terms in smoothing spline ANOVA models. The elimination of practically insignificant terms generally enhances the interpretability of the estimates and sometimes may also have inferential implications. The diagnostics are derived from Kullback‐Leibler geometry and are illustrated in the settings of regression, probability density estimation, and hazard rate estimation.     

深化多媒体教学推进远程教育的发展

本文通过对国内外现代远程教育的探讨,对多媒体教学的分析,提出了我国高等教育要赶超世界先进水平、发展远程教育目前所面临的主要问题及对策.     

师生人际距离新论

人际距离是影响人际关系的一个重要因素,贯穿于整个教育过程中的师生距离是人际关系的重要内容,是影响师生交往,进而影响教育教学效果的一个关键因素.师生距离到底该近还是该远,一直是教育理论界热衷的话题.本文结合多年实践中的教育实例,就师生距离的远近问题作一新探讨与解读.     

Predicting body fat using weight–height indices

While body fat is the most accurate measure of obesity, its measurement requires special equipment that can be costly and time consuming to operate. Attention has thus typically focused on the easier to calculate body mass index (BMI). However, the ability of BMI to accurately identify obesity has been increasingly questioned. This paper focuses attention on whether more general body mass indices are appropriate measures of body fat. Using a data set of body fat, height, and weight measurements, general models are estimated which nest a wide variety of weight–height indices as special cases. In the absence of a race and gender categorisation, the conventional BMI was found to be the appropriate index with which to predict body fat. When such a categorisation was made, however, the BMI was never selected as the appropriate index. In general, predicted female body fat was some 10 kg higher than that of a male of identical build and predicted % body fat was over 11 percentage points higher, but age effects were smaller for females. Considerable racial differences in predicted body fat were found for males, but such differences were less marked for females. The implications of this finding for interpreting recent research on the effect of obesity on health, society, and economic factors are considered.     

A note on measures of similarity based on centrality

This note presents a measure of similarity between connected nodes in terms of centrality based on Euclidean distances, and compares it to ‘assortative mixing’ [Newman, M.E.J., 2002. Assortative mixing in networks. Physical Review Letters 89, 208701], which is based on Pearson correlation coefficient. This study suggests that the measure based on Euclidean distances may be more appropriate for relatively smaller (N < 500) and denser networks.     

A note on LeCam’s bound for the distance between the Poisson binomial and the Poisson distribution

n possibly different success probabilities p ₁, p ₂, ..., p _n is frequently approximated by a Poisson distribution with parameter λ = p ₁ + p ₂ + ... + p _n . LeCam's bound p ² ₁ + p ² ₂ + ... + p _n ² for the total variation distance between both distributions is particularly useful provided the success probabilities are small. The paper presents an improved version of LeCam's bound if a generalized d-dimensional Poisson binomial distribution is to be approximated by a compound Poisson distribution. Received: May 10, 2000; revised version: January 15, 2001     

翻译中心智距离存在的客观性

翻译难是一个众所周知的事实。难的原因有多种,涉及许多内在和外在诸因素,其中有一个不容忽视的成因是译者与原作者之间客观地存在着“心智距离”,即译者在语际传译过程中,受自身诸种内在因素的制约,不可能真正地深入到原作者的内心中去,与原作者同思维、共呼吸,与原作者的意旨彻底复合。当代西方流行的接受美学理论为这一现象作了很好的佐证。