PROGRAM EVALUATION

Program Evaluation and Review Technique (PERT) & Critical Path Method (CPM)



PERT & CPM

The Program (or Project) Evaluation and Review Technique, commonly abbreviated PERT, is a model for project management designed to analyze and represent the tasks involved in completing a given project. The critical path method (CPM) or critical path analysis, is a mathematically based algorithm for scheduling a set of project activities. It is an important tool for effective project management.

PERT is a method to analyze the involved tasks in completing a given project, especially the time needed to complete each task, and identifying the minimum time needed to complete the total project.

PERT was developed primarily to simplify the planning and scheduling of large and complex projects. It was developed by Bill Pocock[citation needed] of Booz Allen Hamilton and Gordon Perhson[citation needed] of the U.S. Navy Special Projects Office in 1957 to support the U.S. Navy's Polaris nuclear submarine project. It was able to incorporate uncertainty by making it possible to schedule a project while not knowing precisely the details and durations of all the activities. It is more of an event-oriented technique rather than start- and completion-oriented, and is used more in projects where time, rather than cost, is the major factor. It is applied to very large-scale, one-time, complex, non-routine infrastructure and Research and Development projects.

This project model was the first of its kind, a revival for scientific management, founded by Frederick Taylor (Taylorism) and later refined by Henry Ford (Fordism). DuPont corporation's critical path method was invented at roughly the same time as PERT.

CPM was developed in the 1950s by the DuPont Corporation at about the same time that Booz Allen Hamilton and the US Navy were developing the Program Evaluation and Review Technique [1] Today, it is commonly used with all forms of projects, including construction, software development, research projects, product development, engineering, and plant maintenance, among others. Any project with interdependent activities can apply this method of scheduling.

The essential technique for using CPM is to construct a model of the project that includes the following:

A list of all activities required to complete the project (typically categorized within a work breakdown structure),

The time (duration) that each activity will take to completion, and

The dependencies between the activities

Using these values, CPM calculates the longest path of planned activities to the end of the project, and the earliest and latest that each activity can start and finish without making the project longer. This process determines which activities are "critical" (i.e., on the longest path) and which have "total float" (i.e., can be delayed without making the project longer). In project management, a critical path is the sequence of project network activities which add up to the longest overall duration. This determines the shortest time possible to complete the project. Any delay of an activity on the critical path directly impacts the planned project completion date (i.e. there is no float on the critical path). A project can have several, parallel, near critical ...