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estimate. As initial estimate for the MM-estimate we use an S-estimate. The S- and the MM-estimates employ bisquare ρ -functions with constants such that the MM-estimate has Gaussian ARE equal to 0.95 and the S-estimate has breakdown point 0.5. In Figure 5 we present QQ-plots of the Mahalanobis norms of the residuals of the MLE and the MM-estimate against the root quantiles of the chi- squared distribution with q degrees of freedom. The QQ-plot of the MM-estimate shows clear outliers. 

In Figure 6 are compared the sorted absolute values of the residuals of the MLE with those corresponding to the MM-estimator for each component of the response. 

The right and left panels of Figure 5 show respectively the QQ-plots of the Mahalanobis norms of the residuals of the MLE and the MM-estimate against the 

