Simulation is widely applied as a practical tool for planning and analysis
in many industries. However, in the case of construction processes, it has
not yet emerged from the research stage into practice. The lack of confiden
ce in selection of a probability distribution function (PDF) for an activit
y duration has limited the use of simulation as a practical tool for constr
uctors. A modified beta(1)-beta(2) plane analysis by AbouRizk and Halpin re
vealed that most of the construction data sets they analyzed laid in the be
ta region. Based on research in experimental psychology, it is recommended
that the subjective information used to define beta parameters include the
minimum and maximum activity durations, as well as the mode and the 75th or
25th percentiles. This paper presents a method to determine a beta PDF for
use in construction simulation modeling.