Testing equality of two normal covariance matrices with monotone missing data

Abstract

The problem of testing equality of two multivariate normal covariance matrices is considered. Assuming that the incomplete data are of monotone pattern, a quantity similar to the Likelihood Ratio Test Statistic is proposed. A satisfactory approximation to the distribution of the quantity is derived. Hypothesis testing based on the approximate distribution is outlined. The merits of the test are investigated using Monte Carlo simulation. Monte Carlo studies indicate that the test is very satisfactory even for moderately small samples. The proposed methods are illustrated using an example.     

The relationship between lifetime health trajectories and socioeconomic attainment in middle age

A large literature demonstrates the direct and indirect influence of health on socioeconomic attainment, and reveals the ways in which health and socioeconomic background simultaneously and dynamically affect opportunities for attainment and mobility. Despite an increasing understanding of the effects of health on social processes, research to date remains limited in its conceptualization and measurement of the temporal dimensions of health, especially in the presence of socioeconomic circumstances that covary with health over time. Guided by life course theory, we use data from the British National Child Development Study, an ongoing panel study of a cohort born in 1958, to examine the association between lifetime health trajectories and socioeconomic attainment in middle age. We apply finite mixture modeling to identify distinct trajectories of health that simultaneously account for timing, duration and stability. Moreover, we employ propensity score weighting models to account for the presence of time-varying socioeconomic factors in estimating the impact of health trajectories. We find that, when poor health is limited to the childhood years, the disadvantage in socioeconomic attainment relative to being continuously healthy is either insignificant or largely explained by time-varying socioeconomic confounders. The socioeconomic impact of continuously deteriorating health over the life course is more persistent, however. Our results suggest that accounting for the timing, duration and stability of poor health throughout both childhood and adulthood is important for understanding how health works to produce social stratification. In addition, the findings highlight the importance of distinguishing between confounding and mediating effects of time-varying socioeconomic circumstances.     

三维实体设计与工程制图课程的改革

三维实体设计是工程设计的必然趋势,设计方法的变革导致企业对人才的新需求,也给传统的工程制图课程体系带来了巨大的冲击。改革与现代生产和人才需求不相适应的教学内容,建立以三维设计为主线,以培养创新思维和创新能力为目标的工程制图新体系,是工程制图课程改革的方向。     

论新闻报道策划的实践意义

新闻报道策划 在近几年的新闻实践中应用非常广泛。就报道主题、整合信息、沟通受众和发挥媒体整体优 势等方面论述了新闻报道策划的实践意义。     

非专业大学英语开设背诵课探讨

从3个方面分析阐述了背诵在外语学习中的重要性,并结合有关教学实践,提出在大学公共英语教学中增开背诵课的设想,并对如何开好背诵课提出一些建议。     

精英意识与大众文化的契合——方方的“警察故事”小说特点探析

纵观方方的警察故事题材的小说,可以见出其创作上的特点及变化,体现了方方对人生及历史新的思索与探讨,表明作者在精英文化与大众文化之间寻找的最佳契合点     

"V 什么V"式的句法、语义、语用分析

"V什么V"式是现代汉语中常用的表否定的句式。它形式上最大的特点是"什么"前后的词语相同,它的基本句法结构是主谓结构;"V什么V"式的基本语义特征是表否定,这是通过"什么"实现的;"V什么V"式的语用特点是表示强烈的否定、表达强烈的意志性及简略性。     

社会转型与党建模式之纵向考察

建设一个什么样的党和怎样建设党的问题 ,是一个历史性的老课题。纵观历史 ,世界上近代政党的出现是由古代社会向近代社会转型所决定的 ;近代社会的发展及各国国情的差别 ,决定了不同时代世界各国工人阶级政党类型的不同。中国共产党也有自己的建党模式 ,这种模式必须随中国社会的转型而修正。今天的中国已开始步入工业———信息社会 ,所以今天中国共产党又必须严肃思考和切实解决党建模式的问题。     

论中国人社会化与心理咨询本土化

不同民族的人具有显著的心理差异。西方心理咨询模式与中国人社会化特点存在显著的矛盾冲突 ,其核心是个人取向与社会取向的矛盾。由此决定了心理咨询在中国的发展必须经历一个本土化过程。     

浅谈网络环境下中学政治课研究性教学模式

基于网络环境下的研究性学习是目前研究性学习与信息技术的整合 ,尤其是与互联网技术整合的崭新课题 ,是当今国际教学改革的一个“亮点” ,探讨网络环境下中学政治课研究性教学模式的新课题。