Testing Symmetry and Homogeneity in the Almost Ideal Demand System with Co-integrated Data using Fully Modified Estimation and the Bootstrap

Conventional seemingly unrelated estimation of the almost ideal demand system is shown to lead to small sample bias and distortions in the size of a Wald test for symmetry and homogeneity when the data are co-integrated. A fully modified estimator is developed in an attempt to remedy these problems. It is shown that this estimator reduces the small sample bias but fails to eliminate the size distortion. Bootstrapping is shown to be ineffective as a method of removing small sample bias in both the conventional and fully modified estimators. Bootstrapping is effective, however, as a method of removing size distortion and performs equally well in this respect with both estimators. Copyright 2005 Blackwell Publishing Ltd.