Estimation of Location Parameters Under Nonnormal Errors and Quadratic Loss

Assuming a statistical model in which the joint distribution of the unobservable errors is drawn from independent univariate Student t's that are identically and symmetrically distributed, the sampling performance of traditional robust estimators and a family of Stein-like estimators are compared and evaluated. These results suggest that under thick-tailed distributions, the relative sampling performances and risk characteristics for a range of nonconventional Stein estimators remains approximately the same as in the case of their normal counterparts. The empirical risk implications of misspecifying the error distribution are investigated.     

Robust test for means when population variances are unequal

We consider the problem of testing the equality of two population means when the population variances are not necessarily equal. We propose a Welch-type statistic, say T^* _c, based on Tiku!s ‘1967, 1980’ modified maximum likelihood estimators, and show that this statistic is robust to symmetric and moderately skew distributions. We investigate the power properties of the statistic T^* _c; T^* _c clearly seems to be more powerful than Yuen's ‘1974’ Welch-type robust statistic based on the trimmed sample means and the matching sample variances. We show that the analogous statistics based on the ‘adaptive’ robust estimators give misleading Type I errors. We generalize the results to testing linear contrasts among k population means     

全面建设小康社会与西部多元文化

全面建设小康社会是实现中华民族伟大复兴的伟大工程。全面建设小康社会 ,加快多民族聚居的西部地区的发展至为关键。而维护和发展西部多元文化对实施西部大开发战略 ,全面建设小康社会具有十分重要意义     

Best monotone M‐estimators

The author shows how to find M‐estimators of location whose generating function is monotone and which are optimal or close to optimal. It is easy to identify a consistent sequence of estimators in this class. In addition, it contains simple and efficient approximations in cases where the likelihood function is difficult to obtain. In some neighbourhoods of the normal distribution, the loss of efficiency due to the approximation is quite small. Optimal monotone M‐estimators can also be determined in cases when the underlying distribution is known only up to a certain neighbourhood. The author considers the e‐contamination model and an extension thereof that allows the distributions to be arbitrary outside compact intervals. His results also have implications for distributions with monotone score functions. The author illustrates his methodology using Student and stable distributions.     

新民居小议

新民居的出现和发展是不可避免的趋势 ,但这趋势并非是无序和无规律的。对建筑师而言 ,对于新民居与传统民居以及现代文明间的相互联系及其发展的研究不仅是学术研究上的需要 ,也是社会发展的需要。     

DCC的制备方法及其在染料合成等工业领域的应用

本文对重要有机合成试剂ＤＣＣ的几种合成方法进行了介绍，同时简述了它的性质及化学反应行为，并着重讨论了ＤＣＣ在染料工业等相关领域的应用，如染料中间体的合成，酸性染料染色及后处理等。     

The Skew‐normal Distribution and Related Multivariate Families*

Abstract. This paper provides an introductory overview of a portion of distribution theory which is currently under intense development. The starting point of this topic has been the so‐called skew‐normal distribution, but the connected area is becoming increasingly broad, and its branches include now many extensions, such as the skew‐elliptical families, and some forms of semi‐parametric formulations, extending the relevance of the field much beyond the original theme of ‘skewness’. The final part of the paper illustrates connections with various areas of application, including selective sampling, models for compositional data, robust methods, some problems in econometrics, non‐linear time series, especially in connection with financial data, and more.     

Identifiability of Finite Mixtures of Elliptical Distributions

Abstract.  We present general results on the identifiability of finite mixtures of elliptical distributions under conditions on the characteristic generators or density generators. Examples include the multivariate t -distribution, symmetric stable laws, exponential power and Kotz distributions. In each case, the shape parameter is allowed to vary in the mixture, in addition to the location vector and the scatter matrix. Furthermore, we discuss the identifiability of finite mixtures of elliptical densities with generators that correspond to scale mixtures of normal distributions.     

论我国高等教育运行机制的过渡与转换

本文认为,我国现阶段的高教运行机制正处于过渡与转换的初始阶段,机制转换的完成需要经历一个较长的过渡时期.为了顺利平稳地完成机制转换,必须构建相应的过渡性目标模式,以此作为从适应产品经济到适应有计划的商品经济的高教运行机制模式转换的中介。因此,今后—个时期高教改革的基本思路就不应只朝一个方向努力,而应以国家职能转变为契机,在国家、社会和学校三方面同时展开,并辅之于教育市场的不断培育和竞争机制的逐步加强。     

日本山梨县城乡一体化现状考察与思考

日本山梨县城乡一体化的现状,从经济结构上看,表现在就业者的产业结构、国民收入及恩格尔系数和社会商品零售额等方面;从基础设施上看,体现在人均铺装道路面积、医疗机构以及上下水状况等公共设施的发展水平上;从人的现代化上看,反映在教育、文化、体育、休闲等方面。它给我们的启示是:城乡一体化是一个长期过程,是一项系统工程,是一种现代文明。