The Akaike information criterion, Are, and the Mallows' C-p, criterion
have been proposed as approximately unbiased estimators for their ris
ks or underlying criterion functions. In this paper we propose modifie
d AIC. and C-p for selecting multivariate linear regression models. Ou
r modified AIC and modified C-p are intended to reduce bias in situati
ons where the collection of candidate models includes both underspecif
ied and overspecified models. In a simulation study it is verified tha
t the modified AIC and modified C-p provide better approximations to t
heir risk functions, and better model selection, than AIC and C-p.