Alston and Chalfant's least squares test for functional form is biased
. A valid test is derived for both univariate and multivariate regress
ion models. An estimation method to account for endogenous left-and ri
ght-hand-side current-period budget shares in the Rotterdam and LA AID
S models is presented. Alston and Chalfant's strenuous rejection of th
e LA-AIDS model in favor of the Rotterdam model is not supported by th
eir data.