We investigate interfuel substitution in the United States using the minflex Laurent demand system and a century of data (from 1919 to 2012). We relax the assumption of constant parameters in the demand system, and also relax the homoskedasticity assumption, instead assuming that the covariance...

We address the estimation of singular demand systems with heteroscedastic disturbances. We relax the homoscedasticity assumption and instead assume that the covariance matrix of the errors of the demand system is time-varying. In doing so, we consider the VECH and BEKK parameterizations of the...