Journal of Multivariate Analysis
Minimax estimators of a covariance matrix
Journal of Multivariate Analysis
Best approximation of the identity mapping: The case of variable finite memory
Journal of Approximation Theory
Estimation of covariance matrices in fixed and mixed effects linear models
Journal of Multivariate Analysis
Optimal multilinear estimation of a random vector under constraints of causality and limited memory
Computational Statistics & Data Analysis
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In this paper, we consider the problem of estimating the covariance matrix and the generalized variance when the observations follow a nonsingular multivariate normal distribution with unknown mean. A new method is presented to obtain a truncated estimator that utilizes the information available in the sample mean matrix and dominates the James-Stein minimax estimator. Several scale equivariant minimax estimators are also given. This method is then applied to obtain new truncated and improved estimators of the generalized variance; it also provides a new proof to the results of Shorrock and Zidek (Ann. Statist. 4 (1976) 629) and Sinha (J. Multivariate Anal. 6 (1976) 617).