PERT Chart

A PERT chart, named for the Program Evaluation and Review Technique, is a project-scheduling diagram that models a project as a network of tasks and their dependencies, used to estimate the shortest possible completion time and to identify the critical path, the sequence of tasks that directly determines the project's overall duration. The United States Navy's Special Projects Office developed PERT in 1957 and 1958, working with the consulting firm Booz Allen Hamilton and the Lockheed Corporation, to plan and coordinate the many interdependent contractors building the Polaris submarine-launched ballistic missile program. PERT differed from the similar, independently developed critical path method by explicitly allowing optimistic, pessimistic and most-likely time estimates for each task, and both techniques became standard tools of industrial project planning.