THE ACCURACY OF GRAVITY MODEL PARAMETER ESTIMATES

Procedures for the derivation of standard errors for parameters and fitted values are considered with reference to a particular formulation of the gravity model. Methods based on maximum likelihood estimation are found to have certain disadvantages associated with the large number of parameters typically involved and poor goodness-of-fit, probably due to the omission of pertinent factors from the model. Alternative empirical procedures are described, with particular attention given to a method based on the use of the Monte Carlo simulation. Two small example data sets are used to compare three procedures, one based on maximum likelihood estimation, a second on a approximation to maximum likelihood estimation under the assumption of a Poisson error structure, and the third on Monte Carlo simulation. The first example data set is designed to contain Poisson variates and the second to contain non-Poisson variates with a variance-to-mean ratio larger than one. For the covering abstract of the symposium see TRIS 452544. (Author/TRRL)

• Supplemental Notes:
  • Proceedings of the Eighth International Symposium on Transportation and Traffic Theory, Toronto, Canada, June 24-26, 1981.
• Corporate Authors:

  Toronto University Press

  Front Campus
  Toronto, Ontario  Canada  M5S 1A6
• Authors:
  • Hurdle, V F
  • Hauser, E
  • Bell, G H
• Conference:
  • Proceedings of the Eighth International Symposium on Transportation and Traffic Theory, Toronto, Canada, June 24-26, 1981.
• Publication Date: 1983

Media Info

• Features: Figures; References; Tables;
• Pagination: p. 65-90

Subject/Index Terms

• TRT Terms: Accuracy; Conferences; Empirical methods; Errors; Estimates; Forecasting; Gravity models; Monte Carlo method; Origin and destination; Poisson ratio; Simulation; Traffic
• Old TRIS Terms: Poissons ratio
• ITRD Terms: 8525: Conference; 6440: Error; 132: Forecast; 690: Gravity model; 687: Origin destination traffic; 9103: Simulation; 755: Traffic
• Subject Areas: Highways; Operations and Traffic Management; Planning and Forecasting;

Filing Info

• Accession Number: 00452549
• Record Type: Publication
• Source Agency: Transport Research Laboratory
• Files: ITRD, TRIS
• Created Date: Jul 31 1986 12:00AM