Project (or Program) Evaluation and Review Technique (PERT) is a technique used to estimate projects or programs. It was created by the U.S. Department of Defense for use with the Polaris Missile Program as an advanced method to address great uncertainty. It was since moved into the public domain. PERT uses a model that requires three probabilistic estimates: optimistic, pessimistic, and most likely, offering a weighted average toward the most likely estimate.
PERT is rarely used these days, but it is a powerful model for estimating tasks and/or projects with extreme uncertainty, and provides an extra level of credibility to the estimate.
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