TABLE OF CONTENTS Two widely used methods for planning and controlling projects are known as the critical path method (CPM) and program evaluation and review technique (PERT). The history of the CPM may be traced back to 1956, when E. I. du Pont de Nemours and Company used a network model for scheduling design- and construction-related activities [27]. The PERT was developed about same time as CPM by a team formed by the U.S. Navy's Special Project Office in 1958. The team included members from the Lockheed Missile System Division and from Booz, Allen, and Hamilton, a consulting company [27].
Usually, the three important factors of concern in a given project are time, cost, and availability of resources, and both (CPM and PERT) can easily handle such factors individually and in combination. In basic theory, CPM and PERT are largely the same. For both methods, the arrow diagram is the graphic model, and the mathematics are also quite similar. However, their important differences are as follows:
CPM is used in situations where the duration times of activities are quite certain (e.g., in construction projects).
PERT is used in situations where the duration times of activities are quite uncertain (e.g., in research and development projects).
For both of these methods to be most applicable, a project must possess the following four characteristics [28]:
Independent jobs or tasks. More specifically, within a given sequence these jobs or tasks can be started, stopped, and performed independently.
Full job completion.
