network paths and completion time
Since PERT (program evaluation and review technique) was first introduced in the late 1950s, project management practitioners and researchers have used it to run an increasing number of diverse applications. Today, many computer packages feature PERT as a tool to help project managers schedule and estimate their projects, analyze critical paths, and define early and late start and completion dates. But what the field has often ignored is PERT's probability features. This paper examines the assumptions and the computational process involved in using PERT to determine probability estimates for project completion time. In doing so, it revises the Z-transform method into a simple process to examine other, potentially critical network paths; it identifies four reasons why project managers are averse to PERT probability estimates and describes the assumptions related to using PERT to analyze probability. It also describes the problems associated with using PERT to compute project completion probability.