DEFINING TRIANGULAR PROBABILITY DISTRIBUTIONS FROM HISTORICAL COST DATA

During the development of an automated cost estimating system, several factors led to the selection of the triangular probability-density function to model historical construction costs. The triangular-density function is customarily used when function parameters are directly estimated by experts. A typical example is for estimating activity durations by identifying a minimum value, a most likely value, and a maximum value. These values are then used to construct triangular-density functions to represent uncertain activity durations. For this work, however, it was necessary to estimate parameters of the triangular-density function using historical cost data. A methodology was developed to generate test data and compare three methods of parameter estimation: maximum likelihood, moment matching, and least-squares curve-fitting techniques. It is concluded that optimized moment matching and least-squares techniques produce more accurate parameter estimates, while maximum likelihood estimation yields less accurate results. It is further concluded that the least-squares minimization method always performed as well as or better than the optimized moment matching technique and was therefore selected as the method of choice for the project.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/oclc/8675438
• Corporate Authors:

  American Society of Civil Engineers

  1801 Alexander Bell Drive
  Reston, VA  United States  20191-4400
• Authors:
  • Back, W E
  • Boles, W W
  • Fry, G T
• Publication Date: 2000-1

Language

• English

Media Info

• Features: Appendices; Figures; References; Tables;
• Pagination: p. 29-37
• Serial:
  • Journal of Construction Engineering and Management
  • Volume: 126
  • Issue Number: 1
  • Publisher: American Society of Civil Engineers
  • ISSN: 0733-9364
  • EISSN: 1943-7862
  • Serial URL: http://ascelibrary.org/journal/jcemd4

Subject/Index Terms

• TRT Terms: Accuracy; Automation; Case studies; Construction; Cost estimating; Costs; Curve fitting; Least squares method; Mathematical models; Maximum likelihood method; Optimization; Probability density functions
• Uncontrolled Terms: Moment matching method; Parameter estimation
• Subject Areas: Administration and Management; Construction; Finance; Highways; I10: Economics and Administration;

Filing Info

• Accession Number: 00783775
• Record Type: Publication
• Contract Numbers: CMS 97-13917
• Files: TRIS
• Created Date: Feb 23 2000 12:00AM