Can Scale and Coefficient Heterogeneity Be Separated in Random Coefficients Models?
There is growing interest in the notion that a significant component of the heterogeneity retrieved in random coefficients models may actually relate to variations in absolute sensitivities, i.e. scale heterogeneity, rather than variations in relative sensitivities. This has in part motivated the development of specialised modelling tools such as the generalized multinomial logit model (G-MNL) model. While not disagreeing with the notion that scale heterogeneity across respondents exists, this paper argues that attempts in the literature to disentangle the two components of heterogeneity are misguided. In particular, the authors show how the various model specifications can in fact simply be seen as different parameterisations, and that any gains in fit are the results of using more flexible distributions, rather than an ability to capture scale heterogeneity. The authors illustrate their arguments through an empirical example and show how the conclusions from past work are based on misinterpretations of model results.
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Supplemental Notes:
- This paper was sponsored by TRB committee ADB40 Transportation Demand Forecasting
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Corporate Authors:
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Authors:
- Hess, Stephane
- Rose, John M
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Conference:
- Transportation Research Board 91st Annual Meeting
- Location: Washington DC, United States
- Date: 2012-1-22 to 2012-1-26
- Date: 2012
Language
- English
Media Info
- Media Type: Digital/other
- Features: References; Tables;
- Pagination: 21p
- Monograph Title: TRB 91st Annual Meeting Compendium of Papers DVD
Subject/Index Terms
- TRT Terms: Choice models; Discrete systems; Empirical methods; Random variables
- Uncontrolled Terms: Discrete choice models; Mixed logit models; Random-coefficient model
- Subject Areas: Planning and Forecasting; Transportation (General); I72: Traffic and Transport Planning;
Filing Info
- Accession Number: 01371039
- Record Type: Publication
- Report/Paper Numbers: 12-1721
- Files: TRIS, TRB
- Created Date: May 25 2012 9:31AM