De l'unicité des estimateurs robustes en régression lorsque le paramètre d'échelle et le paramètre de la régression sont estimés simultanément

Several methods have been suggested to calculate robust M- and G-M -estimators of the regression parameter β and of the error scale parameter σ in a linear model. This paper shows that, for some data sets well known in robust statistics, the nonlinear systems of equations for the simultaneous estimation of β, with an M-estimate with a redescending ψ-function, and σ, with the residual median absolute deviation (MAD), have many solutions. This multiplicity is not caused by the possible lack of uniqueness, for redescending ψ-functions, of the solutions of the system defining β with known σ; rather, the simultaneous estimation of β and σ together creates the problem. A way to avoid these multiple solutions is to proceed in two steps. First take σ as the median absolute deviation of the residuals for a uniquely defined robust M-estimate such as Huber's Proposal 2 or the L₁-estimate. Then solve the nonlinear system for the M-estimate with σ equal to the value obtained at the first step to get the estimate of β. Analytical conditions for the uniqueness of M and G-M-estimates are also given.     

A tolerance interval approach for assessment of agreement in method comparison studies with repeated measurements

This paper generalizes the tolerance interval approach for assessing agreement between two methods of continuous measurement for repeated measurement data—a common scenario in applications. The repeated measurements may be longitudinal or they may be replicates of the same underlying measurement. Our approach is to first model the data using a mixed model and then construct a relevant asymptotic tolerance interval (or band) for the distribution of appropriately defined differences. We present the methodology in the general context of a mixed model that can incorporate covariates, heteroscedasticity and serial correlation in the errors. Simulation for the no-covariate case shows good small-sample performance of the proposed methodology. For the longitudinal data, we also describe an extension for the case when the observed time profiles are modelled nonparametrically through penalized splines. Two real data applications are presented.     

关注行业技术进步弘扬企业自主创新成果

科技期刊作为传播科技成果的主要载体,必须立足于报道本专业学科发展动向,关注本行业技术进步及企业自主创新成果,集中反映本行业前沿技术、热点及趋向性问题,以充分发挥科技载体的导向、引领功能,帮助和推动行业的自主创新及其科研成果的面世.     

PSC评分偏误再探

国家普通话水平测试(PSC)在经历了十年的运行之后,测试研究已逐步趋向于深层次方向的问题探讨,对评分偏误现象及造成评分偏误的因素的研究是其中的一个方面。对造成评分偏误的因素的分析除了要关注测试本身在设计上的一些因素之外,还要关注汉语的特点、测试员的因素以及在测试过程中的各种外在因素。此文同时还试图通过对各种制约因素的梳理,探讨不同等级之间的客观的评分差异。     

浅说希腊哲学中的意志与自由

在西方哲学史中,自由意志理论是一个非常重要的思想资源,它起源于古希腊时期。那时对意志自由思想的探索尚处在朦胧阶段,哲学家们并未对该问题进行专门的研究,只有一些简单粗糙的规定散见于不同哲学派别的学说中,但正是这些粗陋的规定,为整个西方意志自由思想的发展奠定了基础。     

论对偶在汉语写作中的认知意义

对偶是汉语语体系统和文体系统中的重要构成元素,是人们把对世界的认识摹写出来又渗透到高雅文化与民俗文化之中的一种语言表达式。对偶思维是一种耦合①性思维,集中反映了汉民族写作的整体思维和对立统一思维。考察汉语写作史可以发现:对偶不仅仅是传统意义上的一种修辞方式,它更是汉民族写作的一种重要的认知模式。隐喻的研究,已经从一种修辞手段的研究转化为认识世界和语言发生变化的重大课题和焦点课题。而对偶的研究,如对偶的形成与结构体制对汉语写作的认知意义;对偶所映射的汉族人的文化传统、审美心理;对偶的语体学意义和文体学意义;对偶与语体、文体嬗变和社会需求的关系问题等也应该是语言学中极有理论价值和方法论意义的研究课题。     

胡仔《苕溪渔隐丛话》的用事论

胡仔《苕溪渔隐丛话》对用事的探讨是构建其独特诗学理论体系的一个重要组成部分。主要体现在三个方面:首先,他从诗人诗作的用事实例着手,分析诗词用事的偏差与失误;其次,他提出了《苕溪渔隐丛话》用事的标尺———“合理”;最后,表达了他的用事理想———精切。《苕溪渔隐丛话》这种独特用事论无论是在广度还是在深度上,都为后世用事理论的发展奠定了坚实的基础。     

Self-weighted least absolute deviation estimation for infinite variance autoregressive models

Summary.  How to undertake statistical inference for infinite variance autoregressive models has been a long-standing open problem. To solve this problem, we propose a self-weighted least absolute deviation estimator and show that this estimator is asymptotically normal if the density of errors and its derivative are uniformly bounded. Furthermore, a Wald test statistic is developed for the linear restriction on the parameters, and it is shown to have non-trivial local power. Simulation experiments are carried out to assess the performance of the theory and method in finite samples and a real data example is given. The results are entirely different from other published results and should provide new insights for future research on heavy-tailed time series.     

基层妇联干部的职业素养状况与角色期待教育

当前基层妇联干部的素质状况、角色认知、角色认同感及处理多重角色冲突的能力与实际要求有偏差,要增强其服务妇女群众的角色意识、个人职业生涯的发展能力,接受新信息、新观念的能力,以及创造性开展工作的能力和处理多重关系的能力,就必须调整基层妇联干部的角色认知,塑造良好的心理素质和职业素养,以促进男女共同发展,构建社会主义的和谐社会.     

运用离差最大化方法对影响区域经济发展因素的分析

分析了离差最大化方法的特点,通过实证表明,运用离差最大化方法在确定指标权重方面比较客观的优点,分析不同区域经济发展过程中的主要影响因素,可寻求制定区域经济发展对策与措施的客观依据。