Abstract:
This paper deals with the regularity problem in the Almost Ideal Demand System (AIDS) in terms of the boundedness of the budget shares within the [0,1] interval. The violation of "cointegration accounting" can be seen just as another consequence of irregularity. The discussion of modifications in the PIGLOG cost functions leads to the proposition of a modified dynamic PIGLOG formulation, from which a system of budget shares can be derived, which ensures regularity and validity of "cointegration accounting". A special feature of the resulting share equations is the divergence from the time path of the AIDS shares over time.