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Forecasting light-duty vehicle demand using alternative-specific constants for endogeneity correction versus calibration
Journal article   Peer reviewed

Forecasting light-duty vehicle demand using alternative-specific constants for endogeneity correction versus calibration

C. Grace Haaf, W. Ross Morrow, Ines M. L. Azevedo, Elea McDonnell Feit and Jeremy J. Michalek
Transportation research. Part B: methodological, v 84, pp 182-210
01 Feb 2016

Abstract

Business & Economics Economics Engineering Engineering, Civil Operations Research & Management Science Science & Technology Social Sciences Technology Transportation Transportation Science & Technology
We investigate parameter recovery and forecast accuracy implications of incorporating alternative-specific constants (ASCs) in the utility functions of vehicle choice models. We compare two methods of incorporating ASCs: (1) a maximum likelihood estimator that computes ASCs post-hoc as calibration constants (MLE-C) and (2) a generalized method of moments estimator that uses instrumental variables (GMM-IV) to correct for price endogeneity. In a synthetic study we observe significant coefficient bias with MLE-C when the price-ASC correlation (endogeneity) is large. GMM-IV successfully mitigates this bias given valid instruments but exacerbates the bias given invalid instruments. Despite greater coefficient bias, MLE-C yields better forecasts than GMM-IV with valid instruments in most of the cases examined, including most cases where the price-ASC correlation present in the estimation data is absent in the prediction data. In a market study of U.S. midsize sedan sales from 2002 - 2006 the GMM-IV model predicts the 1-year-forward market better, but the MLE-C model predicts the 5-year-forward market better. Including an ASC in predictions by any of the methods proposed improves share forecasts, and assuming that the ASC of each new vehicle matches that of its closest competitor vehicle yields the best long term forecasts. We find evidence that the instruments most frequently used in the automotive demand literature may be invalid. (C) 2015 Elsevier Ltd. All rights reserved.

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Collaboration types
Industry collaboration
Domestic collaboration
Web of Science research areas
Economics
Engineering, Civil
Operations Research & Management Science
Transportation
Transportation Science & Technology
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