Multiple linear regression/Multivariate outliers

==Multivariate outliers== Check whether there are influential multivariate outlying cases using Mahalanobis distance & Cook’s D. Using PASW:
 * Linear Regression - Save - Mahalanobis and Cook's D - OK
 * SPSS will create new variables called mah_1 and coo_1.
 * Check the Residuals Statistics table in the output for the maximum Mahalanobis and Cook’s distances.
 * The maximum Mahalanobis distance should not be greater than the critical chi-square value with degrees of freedom equal to number of predictors, with critical alpha (α) =.001.
 * Cook’s D should not be greater than 1.
 * If outliers are detected, check each case, and consider removing the case from the analysis.
 * See also Francis 5.1.4.2 Screening for influential case