Behavioural response and form of the representative component of the indirect utility function in travel choice models

In the last ten years, discrete-choice modelling using techniques of multinomial logit and multinomial probit, have been increasingly used in a wide range of applications. One area of recent interest is the functional form of the representative component of the preference function. In this paper we draw together a number of approaches used to investigate alternative functional form, and then develop in some detail one procedure — known as the Box-Tukey statistical search approached. While this is not a substitute for direct behavioural specification, it does provide a useful complementary basis for identifying the sensitivity of key policy parameters (e.g., elasticities) to varying functional form. The empirical illustration is drawn from analysis of a mode choice data set.