On some properties of variable size simple random sampling and a limit theorem

This paper introduces a sampling plan for finite populations herein called “variable size simple random sampling” and compares properties of estimators based on it with results from the usual fixed size simple random sampling without replacement. Necessary and sufficient conditions (in the spirit of Hajek (1960)) for the limiting distribution of the sample total (or sample mean) to be normal are given.     

On the distributions of components sums of squares in one-way unbalanced random model under heter06ene0us error variances

Exact sampling distributions of sums of squares in the unbalanced one-way random model are obtained under heterogeneous error variances. These distributions are used to investigate the effect of heteroscedasticity and unbalancedness on the probability of negative estimate of the group variance component. The computed results reveal that heteroscedasticity affects the probability of negative estimate in all situations of group sizes. Further, the probability decreases with heterogeneity of error variances for balanced situations and increases with variability among group size for equal error variances case.     

关于提高大学生班级凝聚力的几点思考

班集体凝聚力的大小直接关系到班风、学风、校风建设的成败。探讨如何提升班集体凝聚力，对提高班级管理水平、促进学生全面发展具有十分重要的意义。影响班级凝聚力的因素可归纳为社会因素和学生自身因素，提高班级凝聚力可从建设好班委学生干部队伍、加强班级民主制度建设等方面入手。     

Joint analysis of longitudinal data and competing terminal events in the presence of dependent observation times with application to chronic kidney disease

In many prospective clinical and biomedical studies, longitudinal biomarkers are repeatedly measured as health indicators to evaluate disease progression when patients are followed up over a period of time. Patient visiting times can be referred to as informative observation times if they are assumed to carry information in addition to that of the longitudinal biomarker measures alone. Irregular visiting times may reflect compliance with physician instruction, disease progression and symptom severity. When the follow-up time may be stopped by competing terminal events, it is possible that patient observation times may correlate with the competing terminal events themselves, thus making the observation times difficult to assess. To explicitly account for the impact of competing terminal events and dependent observation times on the longitudinal data analysis in the context of such complex data, we propose a joint model using latent random effects to describe the association among them. A likelihood-based approach is derived for statistical inference. Extensive simulation studies reveal that the proposed approach performs well for practical situations, and an analysis of patients with chronic kidney disease in a cohort study is presented to illustrate the proposed method.     

仿词漫谈——从“××吧”说开去

仿造是汉语词汇发展的一条重要途经。近几十年来 ,汉语仿词特别丰富 ,这有利于汉语词汇的丰富与发展。但近些年来汉语仿词失之过滥 ,特别是对领导人的常用词语普遍仿造 ,以至造成“千人仿一词 ,万人学一语”的情况 ,对词汇发展并不利。应该避免在仿词上赶时髦的做法     

Interactive effect of individual factors on nurses' health and sleep

Abstract

There is a tendency in studies concerning individual diferences in shiftwork tolerance to analyse the moderating effect of individual factors separately as if they acted independently. The aim of this study was to examine the interactive effect of individual factors (i.e. morningness, flexibility, languidity, neuroticism, extroversion) on nurses' health and sleep. A hundred female nurses (mean age 25.9 years, SD = 3.7 years) working a 2 × 12-h shift system were chosen from a larger study conducted among Intensive Care Unit staff. All subjects completed the Standard Shiftwork Index. Multiple regression analyses show that interactions of neuroticism and other factors (languidity, morningness) predict the majority of health and sleep complaints rather than neuroticism itself. Correlation analyses revealed that the interaction of neuroticism and languidity correlates higher with some indices of impaired health and sleep disturbances than when these factors are taken separately. The contribution of flexibility together with extroversion in interactions with neuroticism, and with neuroticism and languidity weaken the relations of languidity and neuroticism with health and sleep indices. The results show that some individual features tend to strengthen or counteract one another in relation to symptoms of shiftwork intolerance.     

Fairness of the national health service in Italy: a bivariate correlated random effects model

The primary purpose of this paper is to comprehensively assess households’ burden due to health payments. Starting from the fairness approach developed by the World Health Organization, we analyse the burden of healthcare payments on Italian households by modeling catastrophic payments and impoverishment due to healthcare expenditures. For this purpose, we propose to extend the analysis of fairness in financing contribution through a generalized linear mixed models by introducing a bivariate correlated random effects model, where association between the outcomes is modeled through individual- and outcome-specific latent effects which are assumed to be correlated. We discuss model parameter estimation in a finite mixture context. By using such model specification, the fairness of the Italian national health service is investigated.     

Testing for zero-inflation in count series: application to occupational health

Count data series with extra zeros relative to a Poisson distribution are common in many biomedical applications. A score test is presented to assess whether the zero-inflation problem is significant to warrant the analysis by the more complex zero-inflated Poisson autoregression model. The score test is implemented as a computer program in the Splus platform. For illustration, the test procedure is applied to a workplace injury series where many zero counts are observed due to the heterogeneity in injury risk and the dynamic population involved.     

Multichannel electroencephalographic analyses via dynamic regression models with time-varying lag–lead structure

Multiple time series of scalp electrical potential activity are generated routinely in electroencephalographic (EEG) studies. Such recordings provide important non-invasive data about brain function in human neuropsychiatric disorders. Analyses of EEG traces aim to isolate characteristics of their spatiotemporal dynamics that may be useful in diagnosis, or may improve the understanding of the underlying neurophysiology or may improve treatment through identifying predictors and indicators of clinical outcomes. We discuss the development and application of non-stationary time series models for multiple EEG series generated from individual subjects in a clinical neuropsychiatric setting. The subjects are depressed patients experiencing generalized tonic–clonic seizures elicited by electroconvulsive therapy (ECT) as antidepressant treatment. Two varieties of models—dynamic latent factor models and dynamic regression models—are introduced and studied. We discuss model motivation and form, and aspects of statistical analysis including parameter identifiability, posterior inference and implementation of these models via Markov chain Monte Carlo techniques. In an application to the analysis of a typical set of 19 EEG series recorded during an ECT seizure at different locations over a patient's scalp, these models reveal time-varying features across the series that are strongly related to the placement of the electrodes. We illustrate various model outputs, the exploration of such time-varying spatial structure and its relevance in the ECT study, and in basic EEG research in general.     

浅谈外语学习中非智力因素的作用及其培养策略

非智力因素是外语学习活动中最有活力的内因，它对外语学习的影响有时甚至大于智力因素。本文从智力因素、非智力因素的区别谈起，凸现非智力因素在外语学习中的作用，进而指出强化非智力因素的教学策略和方法。