Programme Evaluation and Review Techniques (PERT) & Critical Path Method (CPM)

Abstract

The historical development of PERT and CPM gives some idea of their purpose and nature and helps to explain both their similarities and differences. PERT was developed in the United States during 1950s essentially as a means to plan and accelerate development of ballistic missile. Obviously, a number of uncertainties were associated with this ballistic missile development project. As for example, what research had to be done to accomplish this, and how should it be planned? How long would the research take? PERT was the planning and scheduling techniques to answer these questions. PERT incorporated these uncertainties into a model, which provides a reasonable framework for answering such queries. It has proved to be useful tool in planning and scheduling projects, which consists of numerous activities whose completion times are uncertain and which, although they must be completed in some order, are independent of one another. Fundamental to PERT is the concept of an "event" or the reaching of a certain stage of completion of a project. Also basic is the expected time required to complete activities leading upto that event.