1969/10/01 by J. V. Zidek, James V. Zidek · 3 citations
Mathematics · Decision Sciences · #Random Matrices and Applications #Probability and Risk Models #Statistical Methods and Inference
paper · pdf · doi:10.1214/aoms/1177697393
Suppose that independent normally distributed random vectors, Xn×1 and Yk×1, are observed with E(X) = 0, E(Y) = μ, Cov(X) = σ2I, and Cov(Y) = σ2I. It is known [2, 5] that the best invariant estimator of μ is admissible if k \leqq 2 and inadmissible if k > 2. It is also known [1, 7] that the best invariant estimator of σ is inadmissible. In this paper, these results are extended to show that the best invariant estimator of θ = Aμ + ησ, for a given matrix A and a given vector η, is inadmissible if |η| is sufficiently large (when k = 1, A = 1, θ is a quantile).