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...
Saved in:
Published in | Journal of construction engineering and management Vol. 126; no. 1; pp. 29 - 37 |
---|---|
Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
Reston, VA
American Society of Civil Engineers
01.01.2000
|
Subjects | |
Online Access | Get full text |
Cover
Loading…
Summary: | 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. |
---|---|
Bibliography: | ObjectType-Article-2 SourceType-Scholarly Journals-1 ObjectType-Feature-1 content type line 23 |
ISSN: | 0733-9364 1943-7862 |
DOI: | 10.1061/(ASCE)0733-9364(2000)126:1(29) |