A geometric interpretation of Mallows' C-p statistic and an alternative plot in variable selection

Abstract

Mallows' C-p plot is a useful tool for variable selection in linear regression. Though not as popular as the C-p plot, Spjotvoll's F-p and P-p plots are also used in the variable selection procedure. The C-p, F-p and P-p plots are useful in their own right. If the interest is the direct measure of the amount of bias of the submodels and a distributional assumption is not made about the error term, a C-p or F-p plot is used. If a formal testing procedure is to be performed, then a P-p plot is employed. A geometrical approach is used in order to propose an alternative plot that unifies all the information in these three plots, and that has some advantages over them. A Mathematica package has been written to implement the approach. (c) 2007 Elsevier B.V. All rights reserved.