Combining sources of preference data

This paper brings together several research streams and concepts that have been evolving in random utility choice theory: (1) it reviews the literatur e on stated preference (SP) elicitation methods and introduces the concept of testing data generation process invariance across SP and revealed prefer ence (RP) choice data sources; (2) it describes the evolution of discrete c hoice models within the random utility family, where progressively more beh avioural realism is being achieved by relaxing strong assumptions on the ro le of the variance structure (specifically, heteroscedasticity) of the unob served effects, a topic central to the issue of combining multiple data sou rces; (3) particular choice model formulations incorporating heteroscedasti c effects are presented, discussed and applied to data. The rich insights p ossible from modelling heteroscedasticity in choice processes are illustrat ed in the empirical application, highlighting its relevance to issues of da ta combination and taste heterogeneity. (C) 1999 Elsevier Science S.A. All rights reserved. JEL classification: C25.