两个方差分量同时估计的可容许性

ADMISSIBLITY OF SIMULTANEOUS ESTIMATION OF TWO VARIANCE COMPONENTS

  • 摘要: 考虑方差分量模型\left\\beginarraylE Y=X \cdot \beta \\p \times 1=p \times p \times 1 \\D Y=\sigma_1^2 V_1+ _2^2 V_2,\endarray\right.其中 \beta \in R^p, \sigma_1^2>0, \sigma_2^2>0 均未知; \mathrmX, \nabla_1>0, V_2>0 均已知; r(X)=p 。我们要同时估计 \left(\sigma_1^2, \sigma_2^2\right) ,并考虑估计类 \mathscrP=\left\d\left(A_1, A_2\right)=\left(Y^\prime A_1 Y, Y^\prime A_2 Y\right), A_1 \geqslant 0, A_2 \geqslant 0\right\ 。损失函数为:L\left(d\left(A_1, A_2\right),\left(\sigma_1^2, \sigma_2^2\right)\right)=\frac1\sigma_1^4\left(Y^\prime A_1 Y-\sigma_1^2\right)^2+\frac1\sigma_2^4\left(Y^\prime A_2 Y-\sigma_2^2\right)^2.本文给出了在 V_1=\nabla_2 限制下, d\left(A_1, A_2\right) 为 \mathscrD 容许估计的充分条件和必要条件,以及没有这个限制时 d\left(A_1, A_2\right) 为 9 容许估计的充分条件。

     

    Abstract: Consider a variance-oomponent model \left\\beginarrayl E \undersetp \times 1Y=X \undersetp \times pX \cdot \undersetp \times 1\beta \\ D Y=\sigma_1^2 V_1+\sigma_2^2 V_2, \endarray\right. where \beta \in R^p, \sigma_1^2>0, and \sigma_2^2>0 are all unknown, X, V_1>0 and V_2>0 are all knwon, r(X)=p.The author estimates simultaneously \left(\sigma_1^2, \sigma_2^2\right. ) and oonsiders the estimator class \mathscrX=\left\d\left(A_1, A_2\right)=\left(Y^\prime A_1 Y, Y^\prime A_2 Y\right), A_1 \geqslant 0, A_2 \geqslant 0\right\ . The loss function is L\left(d\left(A_1, A_2\right),\left(\sigma_1^2, \sigma_2^2\right)\right)=\frac1\sigma_1^4\left(Y^\prime A_1 Y-\sigma_1^2\right)^2+\frac1\sigma_2^4\left(Y^\prime A_2 Y-\sigma_2^2\right)^2 . This paper gives both a sufficient condition and a necessary condition for d\left(A_1, A_2\right) to be a \mathscrD-admissible estimator under the restriction V_1=V_2, and a sufficient oondition for d\left(A_1, \Lambda_2\right) to be a 0 -admissible estimator without this restriotion.

     

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