中国沪深股市均值回复效应实证研究——基于GIBBS抽样方法

使用一种新的模拟方法：GIBBS抽样对沪深股市月超额收益率数据进行标准化后,基于VR检验研究两市月度超额收益率是否存在均值回复效应。实证结果表明,1996年到2006年的11年间,在间隔为3-33个月的水平上,沪深股市都不存在均值回复效应,即两个市场都达到了弱式有效,而沪市的有效性大于深市。传统的抽样方法只考虑数据异方差的持续性而忽略异方差的具体形式,文章基于一个Markov-Switch模型进行GIBBS抽样,在估计VR的经验分布时考虑了数据异方差的持续性和具体形式等信息,因此结论更加可靠。     

Semiparametric estimation of employment duration models

There are a variety of economic areas, such as studies of employment duration and of the durability of capital goods, in which data on important variables typically are censored. The standard techinques for estimating a model from censored data require the distributions of unobservable random components of the model to be specified a priori up to a finite set of parameters, and misspecification of these distributions usually leads to inconsistent parameter estimates. However, economic theory rarely gives guidance about distributions and the standard estimation techniques do not provide convenient methods for identifying distributions from censored data. Recently, several distribution-free or semiparametric methods for estimating censored regression models have been developed. This paper presents the results of using two such methods to estimate a model of employment duration. The paper reports the operating characteristics of the semiparametric estimators and compares the semiparametric estimates with those obtained from a standard parametric model.     

Exploratory method for summarizing concomitant medication data – the mean cumulative function

Concomitant Medications are medications used by patients in a clinical trial, other than the investigational drug. These data are routinely collected in clinical trials. The data are usually collected in a longitudinal manner, for the duration of patients' participation in the trial. The routine summaries of this data are incidence‐type, describing whether or not a medication was ever administered during the study. The longitudinal aspect of the data is essentially ignored. The aim of this article is to suggest exploratory methods for graphically displaying the longitudinal features of the data using a well‐established estimator called the ‘mean cumulative function’. This estimator permits summary and a graphical display of the data, and preparation of some statistical tests to compare between groups. This estimator may also incorporate information on censoring of patient data. Copyright © 2009 John Wiley & Sons, Ltd.     

试论翻译的“距离”特质与读者接受

本文探讨了翻译的"距离"特质,指出文化距离是读者接受译作的关键。译者在着手翻译时要"选择"读者,"适应"读者,立体关照读者,提升与"苛求"读者的期待视野,跨越文化距离,争取更大的读者群,扩大译作的接受范围,延长译作的共时和历时寿命。     

Multivariate attribute control chart using Mahalanobis D2 statistic

Process control involves repeated hypothesis testing based on several samples. However, process control is not exactly hypothesis testing as such since it deals with detection of non-random patterns of variation as well in a fleeting kind of population. Compare this with hypothesis testing which is principally meant for a stagnant population. Dr Walter A. Shewhart introduced a graphic method for doing this testing in a fleeting population in 1924. This graphic method came to be known as control chart and is widely used throughout the world today for process management purposes. Subsequently there was much advancement in process control techniques. In particular, when more than one variable was involved, process control techniques were developed mainly by Hicks (1955), Jackson (1956 and 1959) and Montgomery and Wadsworth (1972) based on the pioneering work of Hotelling in 1931. Most of them have worked in the area of multivariate variable control chart with the underlying distribution as multivariate normal. When more than one attribute variables are involved some works relating to test of hypothesis was done by Mahalanobis (1946). These works were also based on the Hotelling T² test. This paper expands the concept of 'Mahalanobis Distance' in case of a multinomial distribution and thereby proposes a multivariate attribute control chart.     

Error misspecification and properties of the simple ridge estimator

This paper gives necessary and sufficient conditions for the ridge estimator applied to an error misspecified regression model to dominate the generalised least squares estimator. It is shown that the requirements for mean square error dominance are more stringent than in the correct specification case.     

Estimation of the mean of the selected gamma population

Let л₁ and л₂ denote two independent gamma populations G(α₁, p) and G(α₂, p) respectively. Assume α(i=1,2)are unknown and the common shape parameter p is a known positive integer. Let Y_i denote the sample mean based on a random sample of size n from the i-th population. For selecting the population with the larger mean, we consider, the natural rule according to which the population corresponding to the larger Y_i is selected. We consider? in this paper, the estimation of M, the mean of the selected population. It is shown that the natural estimator is positively biased. We obtain the uniformly minimum variance unbiased estimator(UMVE) of M. We also consider certain subclasses of estikmators of the form c₁x₍₁₎ +c₁x₍₂₎ and derive admissible estimators in these classes. The minimazity of certain estimators of interest is investigated. Itis shown that p(p+1)^-1x₍₁₎ is minimax and dominates the UMVUE. Also UMVUE is not minimax.     

远程教育中网络课程的设计策略

本文在阐述网络教育基本特点的基础上,根据在网上远程教育研究方面的实践体会,提出了网上课程设计的若干原则,并给出了网络课程设计案例。     

Partial Least Squares: A First-order Analysis

We compare the partial least squares (PLS) and the principal component analysis (PCA), in a general case in which the existence of a true linear regression is not assumed. We prove under mild conditions that PLS and PCA are equivalent, to within a first-order approximation, hence providing a theoretical explanation for empirical findings reported by other researchers. Next, we assume the existence of a true linear regression equation and obtain asymptotic formulas for the bias and variance of the PLS parameter estimator     

浅析放松能力对短距离跑的作用

通过从生理、技术角度分析肌肉放松对短距离跑的作用以及影响短距离跑中放松能力的主要因素,得出加强放松能力的训练对提高短跑运动员的成绩有显著性作用,并提出了一系列与短跑相结合的提高放松能力的训练方法及心理训练方法。