Analyzing Frequencies of Several Types of Events: A Mixed Multinomial-Poisson Approach.

A flexible, generalized Poisson model is combined with the multinomial distribution to jointly predict households' choices among types of trips and frequency of trips. The model is compared with conventional Poisson models. The problem of a time-variant mean for frequencies is also addressed, as well as the mean-variance property of the conventional Poisson model that is avoided by use of the generalized formulation. The generalized model is found to outperform the conventional models. Copyright 1990 by MIT Press.