PERT: Program Evaluation and Review Techniques:

Project Management

PERT, the Project Evaluation and Review Technique, is network-based aid for planning and scheduling the several interrelated tasks in a large and complex project. It was developed during the design and construction of the Polaris submarine in the USA in the year of 1950s, which was one of the most complex tasks ever attempted at the time. Nowadays PERT is routinely used in any large project such as software development, building construction, etc. Supporting software such as Microsoft Project, among others, is available readily. It may seem odd that PERT appears in a book on optimization, but it is frequently compulsory to optimize time and resource constrained systems, and the fundamental ideas of PERT help to organize such an optimization.

The PERT is utilized in the situation when the CPM with single time estimate is unreliable. It is basically the generalization of the former method that offers uncertainty in the activity time. When activity times are difficult to predict in advance, this modified method provide estimated project time. In this modified form of CPM i.e. PERT, or CPM with three activity time estimate, three time unit are considered entitled as optimistic value (maximum time unit), most likely value and pessimistic value (minimum time unit). These time units are described as:

a = Pessimistic Value

b = Optimistic Value

m = Most Likely Value

These three time units not only provide the estimate of activity time, but also give a probability estimate for the completion for the overall network. Here, the estimated activity time is calculated by using a weighted average of a minimum, maximum and most likely estimate.