Estimation effects on powers of two simple test statistics in identifying an outlier in linear models

Author: Sutradhar Brajendra  

Publisher: Taylor & Francis Ltd

ISSN: 0094-9655

Source: Journal of Statistical Computation and Simulation, Vol.77, Iss.4, 2007-01, pp. : 305-328

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Abstract

In this paper, we consider two well known, namely the maximum studentized residual (MSR) and maximum normed residual (MNR), test statistics for the detection of a single outlier in linear models. The regression and variance parameters involved in the test statistics are estimated by the traditional least square method (LSM) as well as by two different robust methods (RMs). It is shown through a simulation study that even though RM when compared with LSM produces better estimates for the parameters of the model in the presence of an outlier, the robust estimates-based MSR and MNR tests are however found to be equally or less powerful than the LS estimates-based MSR and MNR tests. This suggests that one should use the LS estimates-based test for the detection of an outlier. Next, if the LS estimates-based test confirms the presence of an outlier, one should however estimate the parameters by using RM.