By reparameterizing the basic translog and the log translog demand systems and exploiting the fact that the Slutsky matrix must be negative semidefinite but cannot he negative definite, it is shown that a recently proposed simple procedure to maintain locally the curvature property of consumer...

This article considers the hypothesis that preference changes may partly explain observed consumption patterns. A model is developed based on indirect weak separability. The kernel estimator of the regression function models the unknown shape of demad functions, and a parametric structure models...