Robust Estimation in Generalised Linear Models : The Density Power Divergence Approach

Abstract: The generalised linear model (GLM) is a very important tool for analysing real data in biology, sociology, agriculture, engineering and many other application domain where the relationship between the response and explanatory variables may not be linear or the distributions may not be normal in all the cases. However, quite often such real data contain a significant number of outliers in relation to the standard parametric model used in the analysis; in such cases the classical maximum likelihood estimator may fail to produce reasonable estimators and related inference could be unreliable. In this paper, we develop a robust estimation procedure for the generalised linear models that can generate robust estimators with little loss in efficiency. We will also explore two particular cases of the generalised linear model in details -- Poisson regression for count data and logistic regression for binary data -- which are widely applied in real life experiments. We will also illustrate the performance of the proposed estimators through several interesting data examples