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�������������Ӷ�Ԫ��̬�ֲ�, �����ӵ�Լ��������ȷ��ʱ,
����˻���W����, LR�����LM�����Ԥ��������������,
���Թ��������Խ��з���.

In this paper, we proposed the preliminary
test two-parameter estimators based on the Wald (W), the Likelihood
Ration (LR) and the Lagrangian Multiplier (LM) tests, when it is
suspected that the regression parameter may be restricted to a
subspace. The bias and the mean square error (MSE) of the proposed
estimators are derived and compared. The conditions of superiority
of the proposed estimators are obtained.