A COMPARISON OF 2 ALTERNATIVE BEHAVIORAL CHOICE MECHANISMS FOR HOUSEHOLD AUTO OWNERSHIP DECISIONS

Auto ownership modeling plays an important role in travel demand analy sis because it is a key determinant of the travel behavior of individu als and households. Discrete-choice auto ownership models use either a n ordered-response choice mechanism or an unordered-response choice me chanism. The ordered-response mechanism is based on the hypothesis tha t an uni-dimensional continuous latent auto ownership propensity index determines the level of car ownership. The unordered-response mechani sm is based on the Random Utility Maximization principle. This paper p resents the underlying theoretical structures, and identifies the adva ntages and disadvantages, of the two alternative response mechanisms. The paper also compares the ordered-response mechanism (represented by the ordered-response legit model) and the unordered-response mechanis m (represented by the multinomial legit model) empirically using sever al data sets. This comparative analysis offers strong evidence that th e appropriate choice mechanism is the unordered-response structure. As a general guideline, auto ownership modeling must be pursued using th e unordered-response class of models (such as the multinomial legit or probit model) and not using the ordered-response class of models (suc h as the ordered-response legit or probit). (C) 1998 Elsevier Science Ltd.