Quasi-minimax estimation in the general linear regression model

This paper is mainly concerned with minimax estimation in the general linear regression model y = X beta + epsilon under ellipsoidal restrictions on the parameter space and quadratic loss function. We confine ourselves to estimators that are linear in the response vector y. The minimax estimators of the regression coefficient beta are derived under homogeneous condition and heterogeneous condition, respectively. Furthermore, these obtained estimators are the ridge-type estimators and mean dispersion error (MDE) superior to the best linear unbiased estimator b = (X'W-1X)X-1'W(-1)y under some conditions. (C) 2008 Elsevier B.V. All rights reserved.