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.     

Teaching technologies for immigrant children: an exploratory study of elementary school teachers in Russia*

ABSTRACT

Educational institutions are an important setting where psychological, pedagogical, sociocultural, and language adaptation of immigrant children occurs. A number of teaching strategies, practices, approaches, and methods have been described in the literature. In the Russian context, such strategies have been called ‘technologies’. The purpose of the present exploratory study was to describe teaching technologies used by teachers in Russia when working with immigrant students in elementary schools. Responses of forty-five elementary school teachers to open-ended questions describing technologies they use when teaching children with migration backgrounds were analyzed using content analysis. Findings suggest that Russian elementary school teachers used ethno-cultural group, communicative technologies, games, individualized instruction, and differentiated teaching. Many approaches mentioned can be used inclusively with groups of immigrant and non-immigrant students. Importantly, while teachers supplemented classroom instruction with additional Russian language lessons, none mentioned specific techniques for teaching Russian as a non-native language. These findings are discussed in relation to teaching strategies described in the international literature focused on migrant students. Finally, implications for further research are discussed.     

A Bayesian Analysis of Abundance,Trend, and Population Viability for Harbor Seals in Iliamna Lake,Alaska

Harbor seals in Iliamna Lake, Alaska, are a small, isolated population, and one of only two freshwater populations of harbor seals in the world, yet little is known about their abundance or risk for extinction. Bayesian hierarchical models were used to estimate abundance and trend of this population. Observational models were developed from aerial survey and harvest data, and they included effects for time of year and time of day on survey counts. Underlying models of abundance and trend were based on a Leslie matrix model that used prior information on vital rates from the literature. We developed three scenarios for variability in the priors and used them as part of a sensitivity analysis. The models were fitted using Markov chain Monte Carlo methods. The population production rate implied by the vital rate estimates was about 5% per year, very similar to the average annual harvest rate. After a period of growth in the 1980s, the population appears to be relatively stable at around 400 individuals. A population viability analysis assessing the risk of quasi‐extinction, defined as any reduction to 50 animals or below in the next 100 years, ranged from 1% to 3%, depending on the prior scenario. Although this is moderately low risk, it does not include genetic or catastrophic environmental events, which may have occurred to the population in the past, so our results should be applied cautiously.     

运用心理学移情原理消除师生的情感障碍

英语教学的成败是诸多因素相互作用的结果 ,但无论这些因素多么错综复杂 ,主要还是来自教和学两方面。教师和学生能否在教学中相互理解从而形成互动是教学成败的关键。文章将着重讨论师生间营造互动关系中的两个重要环节———情感与移情     

计算机与学术写作(英文)

深大外语系把若干计算机软件应用于英语专业本科学生的写作课教材系列。这不仅有助于学生自修写作技巧,且能为教师节省大量时间,使教师有可能对学生作更多的个别辅导。同时,学生在上写作课的过程中还能掌握一种使用计算机的实际技能。近十年来,中国的飞速发展是史无前例的。西方的技术发展史对中国虽然有启迪作用,但其实际要求与中国相去甚远。在这个意义上,深大的尝试对全中国均具有示范意义。     

英语口语教学刍议

英语口语技能是听、说、读、写四项基本语言技能中很重要的一种技能。要通过课堂教学提高学生口语能力 ,必须从教师、教学方法和学生三方面入手 ,即教师应组织和动员学生积极参与学习 ,采取循序渐进的教学方法 ,发挥学生的主观能动性。学生应有明确的学习目标和计划 ,积极配合老师 ,多说勤炼     

初探高校教学与科研的良性循环

正确认识和处理好教学与科研相互依存和相互矛盾的关系及制约这一关系的诸多因素 ,才能实现高校的人才培养和科研成果双丰收 ,促进教学与科研的良性循环     

论非文科专业人文社会科学教学改革的必然趋势

非文科专业人文社会科学教学改革是时代的呼唤和社会可持续发展的现实要求 ,是 2 1世纪高等教育发展的历史趋势 ,是我国社会主义现代化建设事业的客观需要。     

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。     

大学英语教学改革视野中的"情景教学"特色分析

情景教学体现了英语教学改革整体化、情景化的内在灵魂与要求 ,适应了我国大学英语教学改革的需要。《新编大学英语》采用以学生为中心的主题教学模式 ,通过以生活、图画展现情景 ,以音乐渲染情景 ,以角色扮演创设情景的方式为情景教学的实施与运用提供了基础 ,呈现出鲜明的情景教学特色。