Two-stage Huber estimation

In this paper we propose a new robust estimator in the context of two-stage estimation methods directed towards the correction of endogeneity problems in linear models. Our estimator is a combination of Huber estimators for each of the two stages, with scale corrections implemented using preliminary median absolute deviation estimators. In this way we obtain a two-stage estimation procedure that is an interesting compromise between concerns of simplicity of calculation, robustness and efficiency. This method compares well with other possible estimators such as two-stage least-squares (2SLS) and two-stage least-absolute-deviations (2SLAD), asymptotically and in finite samples. It is notably interesting to deal with contamination affecting more heavily the distribution tails than a few outliers and not losing as much efficiency as other popular estimators in that case, e.g. under normality. An additional originality resides in the fact that we deal with random regressors and asymmetric errors, which is not often the case in the literature on robust estimators.     

从译者的审美意识谈文学作品中非规范语音的翻译

文学翻译特别需要译者的审美意识 ,需要作为审美主体的译者发挥创造性和主观能动性。翻译的过程就是原文的审美再现过程。文学作品的翻译要忠实地译出人物的语言特色 ,再现原文的生动形象。语言的常规优美固然重要 ,但正如残缺美也是美一样 ,在文学作品中 ,人物的非规范语言也是一种美 ,因为它有助于烘托生动活泼的人物形象。因此 ,在翻译中要忠实再现 ,否则会影响译文的准确性、生动性     

Bias Correction in the Dynamic Panel Data Model with a Nonscalar Disturbance Covariance Matrix

Approximation formulae are developed for the bias of ordinary and generalized Least Squares Dummy Variable (LSDV) estimators in dynamic panel data models. Results from Kiviet [Kiviet, J. F. (1995), on bias, inconsistency, and efficiency of various estimators in dynamic panel data models, J. Econometrics68:53-78; Kiviet, J. F. (1999), Expectations of expansions for estimators in a dynamic panel data model: some results for weakly exogenous regressors, In: Hsiao, C., Lahiri, K., Lee, L-F., Pesaran, M. H., eds., Analysis of Panels and Limited Dependent Variables, Cambridge: Cambridge University Press, pp. 199-225] are extended to higher-order dynamic panel data models with general covariance structure. The focus is on estimation of both short- and long-run coefficients. The results show that proper modelling of the disturbance covariance structure is indispensable. The bias approximations are used to construct bias corrected estimators which are then applied to quarterly data from 14 European Union countries. Money demand functions for M1, M2 and M3 are estimated for the EU area as a whole for the period 1991: I-1995: IV. Significant spillovers between countries are found reflecting the dependence of domestic money demand on foreign developments. The empirical results show that in general plausible long-run effects are obtained by the bias corrected estimators. Moreover, finite sample bias, although of moderate magnitude, is present underlining the importance of more refined estimation techniques. Also the efficiency gains by exploiting the heteroscedasticity and cross-correlation patterns between countries are sometimes considerable.     

Generalized Laplacian approximations in Bayesian inference

This paper presents a new Laplacian approximation to the posterior density of η = g(θ). It has a simpler analytical form than that described by Leonard et al. (1989). The approximation derived by Leonard et al. requires a conditional information matrix R_η to be positive definite for every fixed η. However, in many cases, not all R_η are positive definite. In such cases, the computations of their approximations fail, since the approximation cannot be normalized. However, the new approximation may be modified so that the corresponding conditional information matrix can be made positive definite for every fixed η. In addition, a Bayesian procedure for contingency-table model checking is provided. An example of cross-classification between the educational level of a wife and fertility-planning status of couples is used for explanation. Various Laplacian approximations are computed and compared in this example and in an example of public school expenditures in the context of Bayesian analysis of the multiparameter Fisher-Behrens problem.     

结点之辨--对从分科教学论到分科教育学的发展的认识

针对学科教育学中存在的一些认识问题,从教育学的内部分类体系对学科教育学的发展做一梳理分析,指出正是由于对从分科教学论到分科教育学的发展历程认识不清,从而形成了诸多问题纠缠的结点。因此,通过对结点的辨析,变结点为节点,从而使学科教学论理清了自己的纵向直线发展脉络和横向发展脉络,实现了教学论与学科教育学的双向发展,学科教育学也把握住了各分科教育学之间的界线,并形成分科教学论与学科教育学和谐发展的良好态势。     

被遮蔽的"文革"叙事--从《玫瑰门》评论小史谈起

<玫瑰门>是铁凝20世纪80年代后期一部以"文革"为背景的重要作品,但从<玫瑰门>的评论小史可以看到,80年代后半期以来,评论界对"文革"主题的忽略与遮蔽是普遍的.其中对抽象人性的偏爱,导致评论界对铁凝等一些小说家揭开"文革"政治对人性阴暗面的催生和放大,与人性固有之丑陋的合谋真相这一努力,大多视而不见.这一情形与80年代中期开始形成的当代文学观密不可分,也与"瞻前"而非"顾后"的社会文化心理有着内在的联系.     

解读池莉小说创作的主体意识

池莉生活和创作心态朴实平和,这就形成了她独特的平民创作风格。对她创作主体意识的阐释,本文从母性意识、城市情结和真实的自我这三个方面来完成。     

水杨酸-邻菲罗啉三元稀土配合物的合成、表征及抑菌作用

在无水乙醇溶液中合成了六种水杨酸-邻菲罗啉-三元稀土配合物,采用元素分析,红外光谱,差热热重等测试方法进行表征,确定配合物的化学组成为RE(Phen)2(Sa l)2C l.H2O(RE=L a3+,P r3+,N d3+,Sm3+,G d3+,D y3+).研究了稀土配合物的抑菌活性,结果表明三元稀土配合物的抑菌效果较单独的稀土氯化物、邻菲罗啉和水杨酸好.     

Test for homogeneity in Hardy–Weinberg normal mixture model

The phenotype of a quantitative trait locus (QTL) is often modeled by a finite mixture of normal distributions. If the QTL effect depends on the number of copies of a specific allele one carries, then the mixture model has three components. In this case, the mixing proportions have a binomial structure according to the Hardy–Weinberg equilibrium. In the search for QTL, a significance test of homogeneity against the Hardy–Weinberg normal mixture model alternative is an important first step. The LOD score method, a likelihood ratio test used in genetics, is a favored choice. However, there is not yet a general theory for the limiting distribution of the likelihood ratio statistic in the presence of unknown variance. This paper derives the limiting distribution of the likelihood ratio statistic, which can be described by the supremum of a quadratic form of a Gaussian process. Further, the result implies that the distribution of the modified likelihood ratio statistic is well approximated by a chi-squared distribution. Simulation results show that the approximation has satisfactory precision for the cases considered. We also give a real-data example.     

浅谈行政合同主体

本文针对我国学界及司法实践中行政合同主体界定存在的分歧,提出行政合同的显著特征不在于其主体的特殊性,而在于行政合同的签订涉及公共利益,具有超越私法以外的合同条款,从而适用行政法规则。