PERT approach and its modification in project management

PERT (Program Evaluation and Review Technique), was developed for application in projects management where there is uncertainty associated with the nature and duration of activities. It originated in the late 1950s during the U.S. Navy's Polaris Missile System Program. In complex research and development Programs such as this one, there are questions about the kind of research to be done, how long it will take, what stages of development are necessary, and how fast they can be completed-largely because of the uncertainty about the exact nature of the final outcomes. Such projects are contracted as new developments unfold and before problems in technology, materials, and processes can be identified and resolved. Thus, the duration of the project is uncertain, and there is considerable risk that the project will overrun the target completion time to accelerate the Polaris Program a special operations research team was formed in 1958. As a way handling uncertainties in the estimating activity times, the team developed PERT. With the foundation and development of PERT, it has been widely used as a tool for managing large-scale projects, and logically in project management. The traditional approach uses the beta distribution of activity duration and estimates the mean and the variance of activity duration based on the "pessimistic", "optimistic" and "most likely" time estimates. Some people have modified the original three-point PERT estimators to improve the accuracy of the estimates. This article will introduce the traditional PERT method and its new development and modification. Finally, the article gives the brief criticisms of PERT.