On fitting mode specific constants in the presence of new options in RP/SP models

Elisabetta Cherchi, Juan de Dios Ortúzar

Research output: Contribution to journalArticlepeer-review


We treat the problem of fitting alternative specific constants (ASC) in models estimated with a mixture of revealed preference (RP) and stated preference (SP) data to forecast the market shares of new alternatives. This important problem can have non-trivial solutions, particularly when some of the SP alternatives are completely revamped versions of existing ones (i.e., an advanced passenger train replacing a normal railway service). As there is no explicit treatment of this problem in the literature we examined it in depth and illustrated it empirically using data especially collected to analyse mode choice in a corridor to the West of Cagliari. We propose a hopefully useful guide to this art (as no practical recipes seem to serve all purposes). Careful specification of the systematic component of utility functions in RP and SP, including the ASC, serves to illuminate the true nature of the underlying error structure in the different data sets, yielding superior forecasting models.

Original languageEnglish (US)
Pages (from-to)1-18
Number of pages18
JournalTransportation Research Part A: Policy and Practice
Issue number1
StatePublished - Jan 2006


  • Error structure
  • Forecasting new options
  • Model specification
  • RP/SP models

ASJC Scopus subject areas

  • Civil and Structural Engineering
  • Transportation
  • Management Science and Operations Research


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