Measuring Inaccuracy in Travel Demand Forecasting: Methodological Considerations Regarding Ramp Up and Sampling
By Bent Flyvbjerg. 2005
138 citations recorded by the source corpus.
Project promoters, forecasters, and managers sometimes object to two things in measuring inaccuracy in travel demand forecasting: (1) using the forecast made at the time of making the decision to build as the basis for measuring inaccuracy and (2) using traffic during the first year of operations as the basis for measurement. This paper presents the case against both objections. First, if one is interested in learning whether decisions about building transport infrastructure are based on reliable information, then it is exactly the traffic forecasted at the time of making the decision to build that is of interest. Second, although ideally studies should take into account so-called demand “ramp up” over a period of years, the empirical evidence and practical considerations do not support this ideal requirement, at least not for large-N studies. Finally, the paper argues that large samples of inaccuracy in travel demand forecasts are likely to be conservatively biased, i.e., accuracy in travel demand forecasts estimated from such samples would likely be higher than accuracy in travel demand forecasts in the project population. This bias must be taken into account when interpreting the results from statistical analyses of inaccuracy in travel demand forecasting.
Subfields: Building and Construction, Economics and Econometrics, Transportation
View Paper: https://www.semanticscholar.org/paper/0660b6bab9f1a02b06d57a3a902f0668cfb18fa0
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Citations in the corpus
- The Principle of the Malevolent Hiding Hand; or, the Planning Fallacy Writ Large (2015, unknown): “Actual costs are measured as recorded outturn costs; actual benefits as first-year benefits, or a later value as close to this as possible, if available and if first-year benefits were not available 2005) and Flyvbjerg (2005).”
- Quality Control and Due Diligence in Project Management: Getting Decisions Right by Taking the Outside View (2013, methodology): “Please cite this article as: Flyvbjerg, B., Quality control and due diligence in project Journal of Project Management (2012), http://dx.doi.org/10.1016/j.ijproman.2012. information, namely how far the forecast in question is from the ideal, i.e., from zero error. In this case we would obtain none o”
- Survival of the Unfittest: Why the Worst Infrastructure Gets Built-And What We Can Do About it (2009, background): “But there is a dark side to their work, which is remarkably underexplored in the literature (Flyvbjerg, 1996).”
- Policy and Planning for Large-Infrastructure Projects: Problems, Causes, Cures (2005, unknown): “(5) For an explanation of the success of the Bilbao Guggenheim Museum, see Flyvbjerg (2005a).”
- Cost Overruns and Demand Shortfalls in Urban Rail and Other Infrastructure (2007, methodology): “For a more detailed description of the methods involved than that given below (Flyvbjerg et al ., 2002, 2005; Flyvbjerg, 2005).”
- Cost Overruns in Large-scale Transportation Infrastructure Projects: Explanations and Their Theoretical Embeddedness (2010, unknown): “…E: e.j.e.molin@tudelft.nl 5 P.O. Box 5015, 2600 GA, Delft, NL, T: +31(0)152787186, F: +31(0)152782719, E: bertw@tudelft.nl Cost Overruns in Large-scale Transportation Infrastructure Projects: Explanations and Their Theoretical Embeddedness recognised (Flyvbjerg, 2005b, De Bruijn and Leijten, 2007).”