Abstract: This paper studies the biased estimation in linear model with equality restrictions and its diagnostic statistic which can assess the influence of deleting date in the date-deleted model.The conditional generalized ridge-type estimation is proposed,and its relation fomula in different models is given.The upper bound of influence in date-deleted model is derived by using Welsch-Kuh statistic and some properties of eigenvalue,and the effect of diagnostic statistic is  examined by means of a numerical example.

Key words: conditional generalized ridge-type estimation, linear model with equality restrictions, Welsch-Kuh statistic, Cook distance