Finally, the regression analysis of the three study samples provides strong evidence for the sensitivity of the regression results to outliers. For both the total sample and the negative sub-sample, the regression indicators improved significantly after the outliers were removed; however, those of the positive sub-sample worsened. This conclusion is in line with that of Herrmann et al. (2003) and Abdel-Fattah (2008) who argue that extreme observations harm and distort the regression results.