A SIMPLE EXPLANATION OF THE SHAPE OF MULTIPLE CAR OWNERSHIP: A REJOINDER

A simple explanation of the shape of multiple car ownership was proposed by Roulet, J (see TRIS 381623) as a possible improvement on present practice. This note attempts to set out current "best practice" and contrast this with Roulet's proposal. Current best practice follows the work of Bates, Gunn and Roberts (1978, "RR20"). Both Roulet's and the RR20 models relate car ownership only to income and are blinded to the influence of other factors such as household size and location. The author makes a critical examination of both approaches. (TRRL)