ALTERNATIVE ROBUST ESTIMATORS FOR PARAMETERS OF THE LINEAR REGRESSION MODEL

Abstract

This paper considers parameter estimation of the linear regression model with Ramsay-Novick (RN) distributed errors, focusing on its use as an aid to robustness. Positioning within the class of heavy tailed distributions, RN distribution can be defined as the modification of unbounded influence function of a non-robust density so that it has more resistance to outliers. Potential use of this robust density have so far been assessed in Bayesian settings on real data examples and there is a lack of performance assessment for finite samples in classical approach. This study therefore explores its robustness properties when used as error distribution in comparison to normal as well as other alternating heavy-tailed distributions like Laplace and Student-t. An extensive simulation study was conducted for this purpose under different settings of sample size, model parameters and outlier percantages. An efficient data generation of this distribution through random-walk Metropolis algorithm is here also suggested. The results were supported by a real world application on famously known as Brownlee’s stack loss plant data.