chapter  24
Analyzing Variable Time Estimates
ByGary L. Richardson, Brad M. Jackson
Pages 11

This chapter describes the mechanics of variable time analysis and shows how the activity estimates can be translated into a meaningful view of project completion. It demonstrates sample basic mechanics for analyzing project plans for which multiple time estimates for activities are available. Project Evaluation and Review Technique (PERT) relies heavily on empirical mathematical averages and probabilistic distributions in order to produce its output. One of the complicating factors that have inhibited broader PERT adoption is the general level of statistics literacy in organizations. Beta distributions and the central limit theorem offer too many Greek symbols for many to digest. A fundamental value that the PERT model has is its ability to show a probabilistic estimate for project completion. Most project management experts do not rank network modeling with variable time estimating as their most important activity, but it actually provides an improved insight into how the project might progress.