Multiple comparisons of mean vectors with large dimension under general conditions

ABSTRACT

Multiple comparisons for two or more mean vectors are considered when the dimension of the vectors may exceed the sample size, the design may be unbalanced, populations need not be normal, and the true covariance matrices may be unequal. Pairwise comparisons, including comparisons with a control, and their linear combinations are considered. Under fairly general conditions, the asymptotic multivariate distribution of the vector of test statistics is derived whose quantiles can be used in multiple testing. Simulations are used to show the accuracy of the tests. Real data applications are also demonstrated.     

高校宣传思想工作"三贴近"调研报告

宣传思想工作要在“三贴近”上取得新进展,这是十六大以来,以胡锦涛同志为总书记的党中央提出的一项政治要求。中共中央、国务院《关于进一步加强和改进大学生思想政治教育的意见》,明确提出了高校思想政治工作要坚持“三贴近”,这也是当前加强和改进高校宣传工作的基本要求。通过对重庆高校宣传思想工作“三贴近”实践情况的调查,分析了重庆市高校宣传思想工作“三贴近”实践中存在的问题,介绍了重庆市高校宣传思想工作“三贴近”实践过程中值得推广的经验。     

谈论还是发帖?口碑形式对产品拟人化的影响及其顺流效应

拟人化营销是企业赋予品牌个性、增加消费者喜爱度和提高营销沟通效率的有效途径,而产品拟人化信息不仅会出现在企业的产品设计或营销沟通中,还会出现在消费者之间的口碑传播中.运用实验研究方法,对口碑中产品拟人化出现的前因与后果进行了实证检验,结果发现:相比于与他人谈论产品,人们在发帖时对产品进行拟人化的倾向更高;自我—他人关注度在口碑形式(谈论vs.发帖)与产品拟人化倾向之间具有中介作用;在发帖口碑中,自我提升动机会增加产品拟人化倾向,但该效应并不会在谈论口碑中出现.此外,当口碑分享者与受众的人际亲密度较低时,相比于包含推荐信息的口碑,包含拟人化描述的口碑对受众的影响更积极.基于上述研究结果,企业应当鼓励消费者在网络平台分享拟人化口碑,利用拟人化口碑在真实性感知方面的优势,产生积极的口碑说服效果,从而实现更好的销售业绩.     

科技英语汉译之“难”与“切”

科技英语汉译一直以来讲究的是准确、科学。分析科技英语汉译之“难”,并借此总结出一些“难”中求“切”的方法。指出科技英语翻译作为一种文体形式不是僵化的,只要处理恰当,在科技英语翻译中也可体现汉语的艺术。     

Optimal simultaneous confidence bands in simple linear regression

A simultaneous confidence band provides useful information on the plausible range of an unknown regression model. For simple linear regression models, the most frequently quoted bands in the statistical literature include the hyperbolic band and the three-segment bands. One interesting question is whether one can construct confidence bands better than the hyperbolic and three-segment bands. The optimality criteria for confidence bands include the average width criterion considered by Gafarian (1964) and Naiman (1984) among others, and the minimum area confidence set (MACS) criterion of Liu and Hayter (2007). In this paper, two families of exact 1−α$1-\alpha$ confidence bands, the inner-hyperbolic bands and the outer-hyperbolic bands, which include the hyperbolic and three-segment bands as special cases, are introduced in simple linear regression. Under the MACS criterion, the best confidence band within each family is found by numerical search and compared with the hyperbolic band, the best three-segment band and with each other. The methodologies are illustrated with a numerical example and the Matlab programs used are available upon request.     

Projection‐Based Statistical Inference in Linear Structural Models with Possibly Weak Instruments

It is well known that standard asymptotic theory is not applicable or is very unreliable in models with identification problems or weak instruments. One possible way out consists of using a variant of the Anderson–Rubin ((1949), AR) procedure. The latter allows one to build exact tests and confidence sets only for the full vector of the coefficients of the endogenous explanatory variables in a structural equation, but not for individual coefficients. This problem may in principle be overcome by using projection methods (Dufour (1997), Dufour and Jasiak (2001)). At first sight, however, this technique requires the application of costly numerical algorithms. In this paper, we give a general necessary and sufficient condition that allows one to check whether an AR‐type confidence set is bounded. Furthermore, we provide an analytic solution to the problem of building projection‐based confidence sets from AR‐type confidence sets. The latter involves the geometric properties of “quadrics” and can be viewed as an extension of usual confidence intervals and ellipsoids. Only least squares techniques are needed to build the confidence intervals.     

论翻译的认知世界和语篇翻译的认知原则简

对认知主体而言,存在着三个世界,即客现世界、认知世界和语言世界,其中认知世界是客观世界和语言世界的中介。翻译研究与翻译涉及的互动的多重世界,主要是两种语言语篇的语言世界及其反映的客观世界、认知世界,紧密相关。语篇翻译译者应深入分析原文文本的微观语言世界,主要在预测目标读者所具备的认知世界知识和解读译文时可能获得的译文识解的基础上,根据两种语言在语篇表达上的异同,坚持译文与原文在语篇微观认知世界上的最佳相似性这一语篇翻译的认知啄刚,构建译文语篇的做观语言符号世界,借此译文读者便可能获得译者所期待的对译文语篇的认知解读。     

日汉同声传译中常见问题及其对策

由于日汉两种语言所具有的不同特点,给同声传译造成了诸多的困难,影响了同声传译的质量。我们在进行日汉同声传译的时侯,可以采用先听先译、延长或缩短等候时间、预测、弥补、紧跟、切割归纳、调节语速语调语气等对策来解决遇到的困难。     

On making causal claims: A review and recommendations

Social scientists often estimate models from correlational data, where the independent variable has not been exogenously manipulated; they also make implicit or explicit causal claims based on these models. When can these claims be made? We answer this question by first discussing design and estimation conditions under which model estimates can be interpreted, using the randomized experiment as the gold standard. We show how endogeneity – which includes omitted variables, omitted selection, simultaneity, common-method variance, and measurement error – renders estimates causally uninterpretable. Second, we present methods that allow researchers to test causal claims in situations where randomization is not possible or when causal interpretation could be confounded; these methods include fixed-effects panel, sample selection, instrumental variable, regression discontinuity, and difference-in-differences models. Third, we take stock of the methodological rigor with which causal claims are being made in a social sciences discipline by reviewing a representative sample of 110 articles on leadership published in the previous 10 years in top-tier journals. Our key finding is that researchers fail to address at least 66% and up to 90% of design and estimation conditions that make causal claims invalid. We conclude by offering 10 suggestions on how to improve non-experimental research.     

Amemiya's generalized least squares and tests of overidentification in simultaneous equation models with qualitative or limited dependent variables

Amemiya's generalized least squares method for the estimation of simultaneous equation modeis with qualitative or limited dependent variables is known to be efficient relative to many popular two stage estimators. This note points out that test statistics for overidentification restrictions can be obtained as by-products of Amerniya's generalized least squares procedure. Amemiya's procedure is shown to be a minimum chisquare method. The Amemiya procedure is valuable both for efficient estimation and for model evaluation of such models.