Replication/prediction problems in the journey to work

In this paper we will consider gravity models for journeys to work. In applications of the theory it is sometimes assumed that the parameters in such models are fixed. We will provide examples to show that this is not always a reasonable assumption, for instance, when the model is applied to predict how changes in the road transportation network influence commuting flows. Models where the parameters are subject to change usually comply with <nobr><i>C</i>-efficiency</nobr> and random utility theory.