REGRESSION DIAGNOSTIC PLOTS IN 3-D

This article concerns three-dimensional (3-D) added variable and parti al residual plots. We show that the two-dimensional (2-D) added variab le and partial residual plots are included as views in the 3-D plots, and these views are along (parallel to) the regression plane. That is, the 2-D plots are limited views, restricted to a sort of flatland, so they have a limited ability to show what is going on. In the case of just two predictors, recent improvements in the 2-D partial residual p lot, such as the Mallows augmented plot, are also included as views in the 3-D plot, but these views are not along the regression plane.