In transportation modelling it has been widely assumed that household income is well fitted by a gamma distribution, and this distribution has been adopted for almost all category analysis trip generation models. This paper presents results from several surveys and demonstrates that in recent years the fits obtained using the gamma distribution have deteriorated. It is shown that a better representation can be achieved by fitting separate gamma distributions for (I) households with one or more working members and (II) households with no workers. The stability of the distribution parameters over time is analysed using the department of employment's family expenditure surveys between 1965 and 1973. The paper discusses the implications of the findings for trip generation models. (A). /TRRL/

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  • Corporate Authors:

    Printerhall Limited

    29 Newmart Street
    London W1P 3PE,   England 
  • Authors:
    • MacKinder, I H
    • Evans, S E
    • May, R
  • Publication Date: 1975-12

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Filing Info

  • Accession Number: 00138946
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Files: ITRD, TRIS
  • Created Date: Nov 17 1976 12:00AM