PERT Analysis Program Evaluation and Review Technique (PERT) is a variation on Critical Path Analysis that takes a slightly more skeptical view of time estimates made for each project stage (Mind Tools, 2011). To use this method it is necessary to acquire an estimate of the shortest possible time each activity will take, the most likely duration, and the longest time that might be taken if the activity takes longer than expected. This adds another dimension of complexity to the critical path method however it also allows to account for a range in various task durations; which represents something much closer to reality than using just one estimate.

For example, take a construction...

With good weather and no major delays the concrete foundation could be poured in two days. However, this hardly ever actually happens and project delays such as weather could drag the duration out as much as a couple weeks. If it did rain then the construction crews might have to wait a week for the ground to dry out. Therefore using this equation in a PERT analysis allows for a project manager to account for some of the variation in task activities.
The PERT approach was originally developed by the U.S. Navy to manage some of their more complex projects that have numerous dependent activities (Net MBA, 2011). It allowed them to consider the range in various task duration…