Explaining, modelling and measuring the heterogeneity in shipper's value of time

The intention of the present article is to shed light on the heterogeneity of value of time among shippers. In order to deal with this issue, we first look at the reasons for which different shippers may value a time saving differently. This analysis makes use of a distinction between generic goods and specific (tailor made) goods. Subsequently, we analyse how this heterogeneity could be represented in the framework of Mixed Logit which is increasingly popular among the Transport Science research community. We concentrate on the issue of the selection of an adequate distribution for the random coefficients of time and costs attributes. In the final part of this article, we make an estimate of the value of time heterogeneity using data collected from shippers in Italy.