ON ESTIMATING EFFECTS IN CERTAIN BEFORE-AFTER STUDIES

Traffic engineers are often confronted with the problems of having to make a reliable estimate of the effect of a safety measure. It is of course essential to know the impact of the effect since any large-scale use of a safety device has to be decided after weighing the positive effects (number of accidents( against negative effects (e.g. cost) and comparing with alternative devices. The purpose of this paper is to study the estimation in some experimental plans where the choice of experimental units depends on what is observed in the before period. In section two, some notations are introduced and a model for experiments studied is described. In the third section examples of three special models that will be treated in more detail, are given. Section four discusses estimation procedures. In the fifth section, the estimation procedures are applied to three special cases. Asymptotic properties of the estimates are derived. Some simulations are presented in the last section. (TRRL)

• Corporate Authors:

  Stockholm University, Sweden

  P.O. Box 6701
  S-11385 Stockholm,   Sweden 
• Authors:
  • SVENSSON, A A
• Publication Date: 1984

Media Info

• Features: References;
• Pagination: 26 p.
• Serial:
  • Issue Number: 131

Subject/Index Terms

• TRT Terms: Before and after studies; Cost effectiveness; Crash rates; Estimating; Estimation theory; Mathematical models; Measures of effectiveness; Safety; Simulation; Traffic engineering
• Uncontrolled Terms: Effectiveness; Models
• ITRD Terms: 1612: Accident rate; 9148: Before and after study; 5911: Efficiency; 132: Forecast; 6473: Mathematical model; 1665: Safety; 9103: Simulation
• Subject Areas: Highways; Operations and Traffic Management; Planning and Forecasting; Safety and Human Factors; I71: Traffic Theory;

Filing Info

• Accession Number: 00391157
• Record Type: Publication
• Source Agency: Swedish National Road and Transport Research Institute (VTI)
• Report/Paper Numbers: Monograph
• Files: ITRD, TRIS
• Created Date: Jan 30 1985 12:00AM