Abstract
Outliers are observations that appear inconsistent with the rest of the data set [1]. It is not
unusual to find an average of 10% outlying observations in the data set of some processes.
Frequently in regression analysis applications, the data set contains some observations that may
have a profound impact or influence on the fitted least squares regression function. In general,
influential observations are outliers and can have significant influence on the parametric test and
therefore it is not surprising that the detection and accommodation of outliers have received
considerable attention in the literature (for example, [2], [3], [4], [5]).