A Regular Demand System with Commodity-Specific Demographic Effects

Regular consumer demand systems almost invariably employ specifications that involve common functional forms in all equations. When applications involve crosssectional data it is often the case that demographic effects are important. However it is plausible that demographic effects are commodity-specific. In this case, there may be a loss of efficiency if a common functional form across commodities is imposed artificially by entering redundant explanators in demand equations for which specific demographic influences are unwarranted. This paper explores an approach to specifying a complete system of demand equations which is fully regular but which nevertheless allows for commodity-specific variation in the functional form of the demand equations.