协方差改进估计与相依混合效应回归方程

本文首先讨论了广义线性模型Ｙ＝Ｘβ＋ε（ε～（Ｏ，Ｖ））的系数β的最优线性无偏估计是用Ｔ２＝ＸＹ作为伴随变量对最小二乘估计Ｔ１＝（ＸＸ）－１Ｘ１Ｙ进行改进而得到的协方差改进估计．并把所得结果用于经济领域中的线性相依回归方程系统（ＳｅｅｍｉｎｇｌｙＵｎｒｅｌａｔｅｄＲｅｇｒｅｓｓｉｏｎＥｑａｕｔｉｏｎｓＳｙｓｔｅｍ）．然后关于一类线性相依混合效应回归方程系统，提出了一种优化估计方法。     

平衡损失下一般Gauss-Markov模型中回归系数的最优估计（英文）

在平衡损失下,我们研究了一般Gauss-Markov模型中回归系数的最优估计,首先我们得到了线性估计为最佳线性无偏估计的充分必要条件;其次证明了平衡损失下的最佳线性无偏估计在几乎处处意义下是唯一的,并且是普通最小二乘估计和二次损失下最优估计的平衡;最后,我们讨论了最优估计关于损失函数和模型设定的稳健性,并得到了该最优估计在模型误定下具有稳健性的充分必要条件.     

一般半相依回归系统的协方差改进估计

本文讨论了由两个等阶的回归方程组成的半相依系统,运用协方差改进法获得了参数的一个迭代估计序列,并证明了它的协方差阵已知时,处处收敛到最佳线性无偏估计,同时其协方差阵在矩阵偏序意义下单调性,并且给出了当迭代次数亦趋于无穷时,保证其具有相合性的一个条件。     

错误先验假定下Bayes线性无偏估计的稳健性

本文基于错误的先验假定获得了一般线性模型下可估函数的Bayes线性无偏估计(BLUE), 证明了在均方误差矩阵(MSEM)准则和后验Pitman Closeness (PPC)准则下BLUE相对于最小二乘估计(LSE)的优良性, 并导出了它们的相对效率的界, 从而获得BLUE的稳健性.     

Bayes估计的进一步研究及其Pitman最优性

对线性模型参数,讨论了Bayes估计的Pitman最优性,将已有结果进行了改进,去掉了附加条件,证明了在Pitman准则下,Bayes估计一致优于最小二乘估计(LSE),在此基础上,提出了一种基于先验信息的方差分量估计,通过和基于LSE的方差分量估计作比较,证明了新估计是无偏估计且有更小的均方误差．最后,证明了在Pitman准则下生长曲线模型参数的Bayes估计优于最佳线性无偏估计．     

Estimation of an unobservable parameters in the type II constraints in singular linear regression model

In regular linear regression model with the type II constraints the unobservable parameters in the constraints can be estimated by the BLUE of the observable parameters. The BLUE respects the constraints. If the estimator of the observable parameters which is the BLUE in the model without constraints is used, then the estimator of the unobservable parameters is the same.     

James-Stein estimators for time series regression models

The least squares (LS) estimator seems the natural estimator of the coefficients of a Gaussian linear regression model. However, if the dimension of the vector of coefficients is greater than 2 and the residuals are independent and identically distributed, this conventional estimator is not admissible. James and Stein [Estimation with quadratic loss, Proceedings of the Fourth Berkely Symposium vol. 1, 1961, pp. 361-379] proposed a shrinkage estimator (James-Stein estimator) which improves the least squares estimator with respect to the mean squares error loss function. In this paper, we investigate the mean squares error of the James-Stein (JS) estimator for the regression coefficients when the residuals are generated from a Gaussian stationary process. Then, sufficient conditions for the JS to improve the LS are given. It is important to know the influence of the dependence on the JS. Also numerical studies illuminate some interesting features of the improvement. The results have potential applications to economics, engineering, and natural sciences.     

Nonparametric estimation of conditional medians for linear and related processes

We consider nonparametric estimation of conditional medians for time series data. The time series data are generated from two mutually independent linear processes. The linear processes may show long-range dependence. The estimator of the conditional medians is based on minimizing the locally weighted sum of absolute deviations for local linear regression. We present the asymptotic distribution of the estimator. The rate of convergence is independent of regressors in our setting. The result of a simulation study is also given.     

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In this article, we develop efficient robust method for estimation of mean and covariance simultaneously for longitudinal data in regression model. Based on Cholesky decomposition for the covariance matrix and rewriting the regression model, we propose a weighted least square estimator, in which the weights are estimated under generalized empirical likelihood framework. The proposed estimator obtains high efficiency from the close connection to empirical likelihood method, and achieves robustness by bounding the weighted sum of squared residuals. Simulation study shows that, compared to existing robust estimation methods for longitudinal data, the proposed estimator has relatively high efficiency and comparable robustness. In the end, the proposed method is used to analyse a real data set.     

RANDOM WEIGHTING APPROXIMATION IN LINEAR REGRESSION MODELS

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A robustness study in sampling on successive occasions

Summary In this paper, we have undertaken an investigation covering three occasions in sampling on successive occasions with a view to examining efficiency robustness of the best linear unbiased estimator (BLUE) visa-vis certain other potentially conceivable estimators when the usual correlation model breaks down. We have inferred that the BLUE, is by and large, an efficiency robust estimate in the face of unforeseen deviations from the usual correlation model.     

回归系数的混合估计与最小二乘估计的一个新的相对效率

本文对具有附加信息的线性回归模型中的混合估计与最小二乘估计给出了一种新的相对效率,研究了新的相对效率与其它几种相对效率的关系,得出了新的相对效率的上、下界.     

最小二乘估计关于误差分布的稳健性

对于设计矩阵$X$是列降秩的线性统计模型, 本文讨论了最小二乘估计关于误差分布的稳健性, 给出了误差分布的最大类, 使得误差项的分布在此范围内变动时, 最小二乘估计在均方误差矩阵准则下是最优估计.     

Sampling designs for regression coefficient estimation with correlated errors

The problem of estimating regression coefficients from observations at a finite number of properly designed sampling points is considered when the error process has correlated values and no quadratic mean derivative. Sacks and Ylvisaker (1966,Ann. Math. Statist.,39, 66–89) found an asymptotically optimal design for the best linear unbiased estimator (BLUE). Here, the goal is to find an asymptotically optimal design for a simpler estimator. This is achieved by properly adjusting the median sampling design and the simpler estimator introduced by Schoenfelder (1978, Institute of Statistics Mimeo Series No. 1201, University of North Carolina, Chapel Hill). Examples with stationary (Gauss-Markov) and nonstationary (Wiener) error processes and with linear and nonlinear regression functions are considered both analytically and numerically.Research supported by the Air Force Office of Scientific Research Contract No. 91-0030.     

A decomposition of a linear model

In this paper we consider a general linear model in a continuous time. We propose a decomposition of the process which helps us to understand the structure of the model. Moreover, the sufficiency of the BLUE estimator of the expectation of the process can be characterized in terms of the Gaussian character of a component of the decomposition.     

回归系数的广义岭型主相关估计及其优良性

In this paper, we propose a new biased estimator of the regression parameters, the generalized ridge and principal correlation estimator. We present its some properties and prove that it is superior to LSE （least squares estimator）, principal correlation estimator, ridge and principal correlation estimator under MSE （mean squares error） and PMC （Pitman closeness） criterion, respectively.     

一般线性混合模型中的最佳线性无偏估计和谱分解估计

该文在一般线性混合模型中, 研究了固定和随机效应线性组合的估计问题.对观测向量的协方差阵可以为奇异矩阵情形下,导出了该组合的最佳线性无偏估计,并证明了它的唯一性.在一般线性混合模型的特例, 三个小域模型下, 得到了小域均值u_i 和方差分量的谱分解估计. 进而, 获得了基于谱分解估计的两步估计均方误差的二阶逼近.     

Stepwise Estimation of Random Processes

The problem of estimating a continuous-time random process from its observations at appropriately designed sampling points is considered. The quality of an estimator is measured by its integrated mean square error (IMSE). Here, sampling points are designed stepwisely to minimize the IMSE and the best linear unbiased estimator (BLUE) is so determined that the earlier calculations do not have to be repeated with addition of one or more new samples. For random processes whose covariance has a sharp corner at the diagonal, it is shown that essentially, an optimal one-step forward sampling location is one of the midpoints of intervals determined by the current and previous sampling points. Both analytical and numerical examples are considered. This revised version was published online in June 2006 with corrections to the Cover Date.     

Superiority of empirical Bayes estimation of error variance in linear model

In this paper, the Bayes estimator of the error variance is derived in a linear regression model, and the parametric empirical Bayes estimator (PEBE) is constructed. The superiority of the PEBE over the least squares estimator (LSE) is investigated under the mean square error (MSE) criterion. Finally, some simulation results for the PEBE are obtained.     

约束条件下线性模型协方差阵扰动的影响分析

该文研究了协方差阵扰动和数据删除对最佳线性无偏估计(BLUE)的影响问题, 给出了在约束条件下一般线性模型与在约束条件下Gauss-Markov模型及在约束条件下数据删除模型中回归参数β的BLUE之间的关系式. 作者还定义了度量影响大小的广义Cook距离D_V并给出了D_V的两个计算公式.