CIRJE-F-162 "Estimating the Covariance Matrix: A New Approach"
Author Name Kubokawa, Tatsuya and M. S. Srivastava
Date July 2002
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Remarks Revised version of CIRJE-F-52 (1999); subsequently published in Journal of Multivariate Analysis, 2003, vol.86, pp.28-47.
Abstract

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 Shorro k and Zidek (1976)and Sinha (1976).