共查询到19条相似文献,搜索用时 189 毫秒
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方差分量的非负二次同时估计的可容许性 总被引:3,自引:0,他引:3
设方差分量模型,其中β∈为未知参数,X已知,V1≥0,V2≥0为已知的非负定矩阵.文[1]在一定的条件下给出了非负二次估计可容许的一个充分必要条件.但必要条件是在x=In(单位矩阵),V1=V2>0的条件下给出的,由于这些限制使必要条件不理想.本文去掉了这些限制,对一般的方差分量模型,给出了与文[1]中一样的必要条件,同时也研究了非齐次二次估计的可容许性. 相似文献
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在二次矩阵损失函数下研究了协方差矩阵未知的多元线性模型中回归系数矩阵的可估线性函数的矩阵非齐次线性估计的可容许性,给出了矩阵非齐次线性估计在线性估计类中可容许的一个充要条件. 相似文献
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《数学物理学报(A辑)》2010,(6)
该文研究了协方差矩阵未知的多元线性模型中,二次矩阵损失函数下回归系数矩阵可估线性函数的非齐次线性估计的可容许性.不需正态分布的假设,作者给出矩阵非齐次线性估计在线性估计类中可容许的充要条件;在正态分布的假设下,作者给出矩阵非齐次线性估计在一切估计组成的估计类中可容许的充分条件. 相似文献
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本文对具有 p 个方差分量的线性模型讨论了方差分量线性函数的 Bayes 不变二次估计问题,给出了 Bayes 不变二次估计(无偏和有偏)的显示表达式,并且证明了它们在各自考虑的类中形成了可容许估计的完全类.在可容许估计的完全类中,还讨论了非负参数函数的非负估计问题,给出了可容许的非负定估计存在的充要条件. 相似文献
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不等式约束下线性模型中线性估计的可容许性 总被引:6,自引:0,他引:6
研究了线性模型在不等式约束条件下齐次和非齐次线性估计的可容许性,刻画了两者之间的关系,得到了不等式约束条件下非齐次线性估计可容许性的充要条件. 相似文献
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本文研究了带有不等式约束的多指标线性模型中线性估计的可容许性.利用矩阵论的相关知识,在矩阵损失下得到了齐次线性估计在齐次线性估计类中是可容许的充要条件,以及非齐次线性估计在非齐次线性估计类中是可容许的若干条件,推广了不等式约束下可容许性的相关结果. 相似文献
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This article considers the admissibility of the linear estimators for the regression coefficients in the growth curve model subject to an incomplete ellipsoidal restriction. The necessary and sufficient conditions for linear estimators to be admissible in classes of the homogeneous and non-homogeneous linear estimators, respectively, are obtained under the quadratic loss function. They are generalizations of some existing results in literature. 相似文献
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Some modifications of improved estimators of a normal variance 总被引:1,自引:1,他引:0
Nobuo Shinozaki 《Annals of the Institute of Statistical Mathematics》1995,47(2):273-286
Consider the problem of estimating a normal variance based on a random sample when the mean is unknown. Scale equivariant estimators which improve upon the best scale and translation equivariant one have been proposed by several authors for various loss functions including quadratic loss. However, at least for quadratic loss function, improvement is not much. Herein, some methods are proposed to construct improving estimators which are not scale equivariant and are expected to be considerably better when the true variance value is close to the specified one. The idea behind the methods is to modify improving equivariant shrinkage estimators, so that the resulting ones shrink little when the usual estimate is less than the specified value and shrink much more otherwise. Sufficient conditions are given for the estimators to dominate the best scale and translation equivariant rule under the quadratic loss and the entropy loss. Further, some results of a Monte Carlo experiment are reported which show the significant improvements by the proposed estimators. 相似文献
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It is already known that the uniformly minimum variance unbiased (UMVU) estimator of the generalized variance always exists
for any natural exponential family. However, in practice, this estimator is often difficult to obtain. This paper provides
explicit forms of the UMVU estimators for the bivariate and symmetric multivariate gamma models, which are diagonal quadratic
exponential families. For the non-independent multivariate gamma models, it is shown that the UMVU and the maximum likelihood
estimators are not proportional.
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随机效应模型中方差分量渐近最优的经验Bayes估计 总被引:3,自引:0,他引:3
本文在加权二次损失下导出了双向分类随机效应模型中方差分量的Bayes估计,并利用多元密度函数及其混合偏导数核估计的方法构造了方差分量的经验Bayes(EB)估计.在适当的条件下证明了EB估计的渐近最优性,给出了模型的特例和推广.最后,举出一个满足定理条件的例子. 相似文献
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《Comptes Rendus de l'Academie des Sciences Series IIA Earth and Planetary Science》2001,332(4):351-356
Within the framework of the non-Gaussian natural exponential families, we construct two UMVU estimators of the generalized variance according to whether the distribution is infinitely divisible or not. This result improves Kokonendji and Seshadri [5] and we can calculate their variance for the simple quadratic families. The multinomial and Poisson-Gaussian cases are studied. 相似文献
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对于平衡线性混合模型,本文提出了一组易验证的条件,在此条件下,方差分量的谱分解估计、方 差分析估计和最小范数二次无偏估计都相等且为一致最小方差无偏估计.同时证明了在此条件下,似然 方程和限制似然方程都有显式解,还给出了许多满足这组条件的平衡线性混合模型的例子. 相似文献
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对于带有不完全椭球约束的生长曲线模型Y=XBZ+ε,ε~(0,σ2VI),X(B-B0)Z′NZ(B-B0)′X′≤σ2In,本文在矩阵损失函数(d-KBL)(d-KBL)′下给出了KBL在类齐次线性估计类LH与非齐次线性估计类LI中可容许的充要条件.本文的结果表明线性估计在非齐次线性估计类中的可容许性与椭球的中心B0无关,而齐次线性估计在齐次线性估计类中的可容许性与B0有关. 相似文献