Estimation of the intercept parameter for linear regression model with uncertain non-sample prior information

This paper considers alternative estimators of the intercept parameter of the linear regression model with normal error when uncertain non-sample prior information about the value of the slope parameter is available. The maximum likelihood, restricted, preliminary test and shrinkage estimators are considered. Based on their quadratic biases and mean square errors the relative performances of the estimators are investigated. Both analytical and graphical comparisons are explored. None of the estimators is found to be uniformly dominating the others. However, if the non-sample prior information regarding the value of the slope is not too far from its true value, the shrinkage estimator of the intercept parameter dominates the rest of the estimators.     

Semiparametric Time-Varying Coefficients Regression Model for Longitudinal Data

Abstract.  In this paper, we consider a semiparametric time-varying coefficients regression model where the influences of some covariates vary non-parametrically with time while the effects of the remaining covariates follow certain parametric functions of time. The weighted least squares type estimators for the unknown parameters of the parametric coefficient functions as well as the estimators for the non-parametric coefficient functions are developed. We show that the kernel smoothing that avoids modelling of the sampling times is asymptotically more efficient than a single nearest neighbour smoothing that depends on the estimation of the sampling model. The asymptotic optimal bandwidth is also derived. A hypothesis testing procedure is proposed to test whether some covariate effects follow certain parametric forms. Simulation studies are conducted to compare the finite sample performances of the kernel neighbourhood smoothing and the single nearest neighbour smoothing and to check the empirical sizes and powers of the proposed testing procedures. An application to a data set from an AIDS clinical trial study is provided for illustration.     

A modified false discovery rate multiple-comparisons procedure for discrete data, applied to human immunodeficiency virus genetics

Summary.  To help to design vaccines for acquired immune deficiency syndrome that protect broadly against many genetic variants of the human immunodeficiency virus, the mutation rates at 118 positions in HIV amino-acid sequences of subtype C versus those of subtype B were compared. The false discovery rate (FDR) multiple-comparisons procedure can be used to determine statistical significance. When the test statistics have discrete distributions, the FDR procedure can be made more powerful by a simple modification. The paper develops a modified FDR procedure for discrete data and applies it to the human immunodeficiency virus data. The new procedure detects 15 positions with significantly different mutation rates compared with 11 that are detected by the original FDR method. Simulations delineate conditions under which the modified FDR procedure confers large gains in power over the original technique. In general FDR adjustment methods can be improved for discrete data by incorporating the modification proposed.     

假设检验的一个常见误区

文章通过对假设检验的一个常见错误进行了理论分析,指出假设检验的方法只能在一定情况下否定原假设而不能肯定原假设,并提出了设定原假设和备择假设的正确而简明的方法。     

论模糊数学在假设检验中的应用

文章通过对隶属函数的集中度系数确定的探讨,将模糊数学应用于贝叶斯统计学,从而形成了一种新的假设检验方法.     

虚拟空间交织的取向原则

虚拟空间交织是人们常用的思维与认知方式之一。本文通过对交织及其原则的介绍,描述了虚拟空间交织的运作,指出虚拟空间交织构建中主观取向的原则应为最佳关联。     

基于视听说网络的大学英语自主学习效果实证研究

国内外许多学者对自主学习进行了大量探讨与研究,但大部分都限于对自主学习能力的界定、对其理论依据和实施策略等进行阐述与分析,几乎没有相关的实证研究。基于此有必要运用实证研究,把学习者在自主学习中各个级别的测试成绩(包括听力、词汇、语法、拼写、口语五个方面)作为一因变量,分析大学生在视听说网络教学模式下自主学习的效果,以了解自主学习对大学英语教学的积极作用以及存在的问题。     

用工业CT技术测量储层岩芯饱和度分布

认识储层岩石中含油饱和度及饱和度分布,对驱替机理的深入研究是非常重要的。为了搞清储层岩石在驱替过程中的饱和度分布情况,应用工业CT技术,提出了一种储层含油岩芯被驱替后的饱和度分布的CT密度差测量方法。在岩样的同一断面,分别对干岩样、饱和岩样及在驱替后的岩样进行CT扫描,重建相应的断层图象,测量所建图象的灰度值,计算出相应的密度值,用密度差法计算出饱和度及其分布值。在γ射线工业CT机“CD-300BG”上对某油田岩样进行了实际测量,获得的结果说明,采用CT密度差法测量饱和度分布是有效的。该方法与常规驱替法相比较,具有快速、精度高、无损岩样和能模拟地层状态测量等特点,是油田开发、油藏描述和地层评价的一种新的有效方法。     

企业职工技能鉴定存在问题分析及对策研究

论述了目前企业职工技能鉴定工作中所存在的问题,阐析了产生这些问题的原因。在此基础上提出企业在发展壮大过程中必须规范企业职工技能鉴定体制,健全职业鉴定制度,充分发挥职业技能考核员作用,同时引进激励约束机制等一系列具体对策。     

简析社会学理论检验中的演绎方法

通过介绍和分析社会学中的演绎逻辑,提出演绎逻辑在社会学理论检验过程中具有假设推演的重要作用,这同它在自然科学中扩充知识的功能不同。社会学中的演绎逻辑具有逻辑演绎和经验演绎两种类型,它们具有各自的优点及不足,因此在社会学理论检验过程中应将两者有机结合,扬长避短。