Unaliasing of aliased line component frequencies

This paper is concerned with undoing aliasing effects, which arise from discretely sampling a continuous‐time stochastic process. Such effects are manifested in the frequency‐domain relationships between the sampled and original processes. The authors describe a general technique to undo aliasing effects, given two processes, one being a time‐delayed version of the other. The technique is based on the observations that certain phase information between the two processes is unaffected by sampling, is completely determined by the (known) time delay, and contains sufficient information to undo aliasing effects. The authors illustrate their technique with a simulation example. The theoretical model is motivated by the helioseismological problem of determining modes of solar pressure waves. The authors apply their technique to solar radio data, and conclude that certain low‐frequency modes known in the helioseismology literature are likely the result of aliasing effects. The Canadian Journal of Statistics 38: 116–135; 2010 © 2010 Statistical Society of Canada     

Variability explained by covariates in linear mixed‐effect models for longitudinal data

Variability explained by covariates or explained variance is a well‐known concept in assessing the importance of covariates for dependent outcomes. In this paper we study R² statistics of explained variance pertinent to longitudinal data under linear mixed‐effect models, where the R² statistics are computed at two different levels to measure, respectively, within‐ and between‐subject variabilities explained by the covariates. By deriving the limits of R² statistics, we find that the interpretation of explained variance for the existing R² statistics is clear only in the case where the covariance matrix of the outcome vector is compound symmetric. Two new R² statistics are proposed to address the effect of time‐dependent covariate means. In the general case where the outcome covariance matrix is not compound symmetric, we introduce the concept of compound symmetry projection and use it to define level‐one and level‐two R² statistics. Numerical results are provided to support the theoretical findings and demonstrate the performance of the R² statistics. The Canadian Journal of Statistics 38: 352–368; 2010 © 2010 Statistical Society of Canada     

Semiparametric median residual life model and inference

For randomly censored data, the authors propose a general class of semiparametric median residual life models. They incorporate covariates in a generalized linear form while leaving the baseline median residual life function completely unspecified. Despite the non‐identifiability of the survival function for a given median residual life function, a simple and natural procedure is proposed to estimate the regression parameters and the baseline median residual life function. The authors derive the asymptotic properties for the estimators, and demonstrate the numerical performance of the proposed method through simulation studies. The median residual life model can be easily generalized to model other quantiles, and the estimation method can also be applied to the mean residual life model. The Canadian Journal of Statistics 38: 665–679; 2010 © 2010 Statistical Society of Canada     

Smoothed empirical likelihood confidence intervals for the relative distribution with left‐truncated and right‐censored data

The study of differences among groups is an interesting statistical topic in many applied fields. It is very common in this context to have data that are subject to mechanisms of loss of information, such as censoring and truncation. In the setting of a two‐sample problem with data subject to left truncation and right censoring, we develop an empirical likelihood method to do inference for the relative distribution. We obtain a nonparametric generalization of Wilks' theorem and construct nonparametric pointwise confidence intervals for the relative distribution. Finally, we analyse the coverage probability and length of these confidence intervals through a simulation study and illustrate their use with a real data set on gastric cancer. The Canadian Journal of Statistics 38: 453–473; 2010 © 2010 Statistical Society of Canada     

第二产业生产服务与服务业生产率——基于面板数据的实证研究

根据经济与合作发展组织发布的24个国家投入产出表,文章分别计算了1995年、2000年和2005年各国服务业劳动生产率,采用面板数据模型检验了第二产业生产服务发展对服务业生产率,以及对服务业就业和产出的影响。检验结果表明,当用于第二产业的服务中间需求不断增加时,服务业劳动生产率将随之提高,与此同时,会带来服务业就业人数的增加,并且对服务业产出有显著的促进作用。     

职业中专学校心理危机干预机制的建设初探

职业中专学生心理危机的存在,迫切要求建设心理危机干预机制。心理危机干预机制是一个系统工程,预防教育制度、早期预警制度、危机干预制度、后期跟踪制度、责任追究制度等是危机干预机制建设的重要内容。     

普通法侵权行为中次级责任解读

侵权行为中的次级责任是指一方当事人应为另一方的侵权行为承担的法律责任。普通法中次级责任通常包括替代责任、共同责任、以及企业责任等。通过对普通法系侵权行为中的"次级责任"及英美国家中相关案例进行解读和分析能为明确中国法律意义上的侵权责任提供启示和帮助,促进中国法律的完善与适用。     

广西中学校长基本现状探析

校长对学校的发展具有决定性的作用。为了了解当前广西中学校长的现状及其在学校治理中面临的问题,笔者对参加广西校长培训的部分中学校长进行了问卷调查。调查发现,校长们面临着学校发展的定位、校长素质的提高、经费短缺、责任压力与激励缺失及资源整合压力等问题。而要解决这些问题,就必须促进校长专业化发展,建立校长激励机制,加大对学校发展的支持力度。     

外语学习信息加工特殊心理机制探究

本文作者认为,外语学习信息加工过程会分为初始、后续和高级三个阶段,各个阶段信息的输入、加工与储存在途径和方式上都不尽相同,并明确指出:(1)外语学习信息加工存在有"初次加工和二次加工"的功能特征;(2)习得母语后处于"冬眠"状态的UG系统,会在外语学习从后续阶段向高级阶段的过渡过程中,受神经网络相关系统的作用而重新启动,生成外语语言-思维结构系统,这一结构系统会与外语知识-认知结构系统一起,共同参与信息加工处理,构成外语学习信息加工特殊心理机制。     

如何进行中学历史课堂提问

课堂提问是中学历史课堂教学的重要手段。要提好问 ,应做到以下几点 :提问要紧扣教材与大纲 ;提问应把握时机 ,形式多样 ;提问得讲求效果 ,注意质与量的统一 ;在提问时教师要积极引导 ,帮助学生形成正确的答案 ;教师对学生的回答应及时小结和评价 ;教师一方面提问学生 ,一方面要鼓励学生多提问