THE USE OF DUMMY VARIABLES IN TRIP GENERATION ANALYSIS

IN MANY INSTANCES OF MODEL FORMULATION, APPROXIMATIONS ARE MADE FOR SIMPLICITY IN COMPUTATION. MOST OFTEN THE ASSUMPTIONS ARE MADE WITH A KNOWLEDGE OF PROBABLE DISCREPANCY. HOWEVER, IT IS NOT ALWAYS, A PROFITABLE TRADE- OFF THAT RESULTS IN SUBSTITUTING SIMPLICITY FOR COMPLEXITY. THIS IS PARTICULARLY TRUE WHEN USING LINEAR REGRESSION TECHNIQUES. REGRESSION ANALYSIS IS USED EXTENSIVELY IN THE TRANSPORTATION PLANNING AREA, PERHAPS BECAUSE OF ITS SIMPLICITY OF COMPREHENSION AND COMPUTATION. METHODOLOGY IN THIS PRESENTATION HAS BEEN REVIEWED FOR TREATMENT OF (1) NON-LINEAR AND (2) DISCRETE RELATIONSHIPS IN LINEAR REGRESSION ANALYSIS. THIS METHODOLOGY HAS DIRECT APPLICATION TO TRIP GENERATION ANALYSIS USED IN URBAN TRANSPORTATION PLANNING. THE TECHNIQUE OF DUMMY VARIABLES IS EXPLORED IN GREAT DETAIL. A DERIVATION OF THE MATHEMATICAL RELATIONSHIPS WHICH LEAD TO THE MODEL FORMULATION IS MADE. WHEN PROBLEMS OF NON-LINEARITY AND CATEGORY TYPE VARIABLES DO NOT EXIST, IT IS NOT RECOMMENDED THAT THE DUMMY VARIABLE TECHNIQUE BE USED. THE DUMMY VARIABLE TECHNIQUE IS SIMPLY A TOOL TO AID THE ANALYST IN MODEL BUILDING. THIS TECHNIQUE, LIKE MOST OTHERS, HAS BOTH ADVANTAGES AND DISADVANTAGES. IT DOES SEEM TO AID IN THE INTERPRETATION OF MORE COMPLEX NONLINEAR AND CATEGORY TYPE VARIABLES. IN MANY CASES A MORE CLEAR AND CONCISE ANALYSIS CAN BE MADE USING THE DUMMY VARIABLE TECHNIQUE THAN IN THE TRANSGENERATION OF THE INDEPENDENT VARIABLES. THE PARTICULAR APPROACH TO THE USE OF DUMMY VARIABLES TAKEN IN THIS PRESENTATION REPRESENTS ONLY ONE OF SEVERAL APPROACHES. THOSE USING THE DUMMY VARIABLE TECHNIQUE IN TRIP GENERATION ANALYSIS SHOULD BE FAMILIAR WITH THE PROBLEMS INHERENT IN MODEL DEVELOPMENT. INEXPERIENCED PERSONNEL APPLYING THIS TECHNIQUE WILL OFTEN FIND THAT IT CAN LEAD TO ERRONEOUS RESULTS. /TR/

  • Authors:
    • Heathington, K W
    • Isibor, E
  • Publication Date: 1972-6

Media Info

  • Features: References; Tables;
  • Pagination: p. 131-42
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00228202
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Aug 31 1972 12:00AM