Identifying the Influence of Stated Choice Design Dimensionality on Willingness to Pay for Travel Time Savings

This paper explores the influence of the dimensions of stated choice (SC) designs on the value of travel time savings. Utilising principles of experimental design, 16 choice designs are embedded within a global design in which we vary the number of choice sets, the number of alternatives in each choice set, the number of attributes per alternative, the number of levels of each attribute, and the range of attribute levels. A mixed logit model is estimated in which design dimensions are interacted with the attribute parameters to explore the influence of these dimensions on willingness to pay (WTP) for travel time savings. The evidence in the context of a sample of respondents in Sydney choosing amongst trip attribute bundles for their car commuting trip suggests that design dimensionality does influence variations in WTP, with higher overall mean values of travel time savings associated with more complex designs, in terms of the number of items to process. © 2004 LSE and the University of Bath