PERT and CPM were both developed at the same time i.e. in midfifties. Both are widely used in planning and controlling the projects. The networking principles used in both the techniques are more or less the same. There are certain differences between the two which are listed in the following chart.
Difference Between PERT and CPM
|The origin of PERT is defence (navy)
|The origin of CPM is industry (Chemical Plant)
|It is event an oriented approach.
|It is an activity oriented system.
|There is allowance for uncertainty.
|It does allow not any uncertainity.
|It is a probabilistic model with uncertainty in activity duration.
|It is a deterministic model with well known activity time based past on experiences.
|It is time based.
|It is cost based.
|It does not demarcate between critical and non-critical events.
|It marks critical activities.
|Time is averaged in it.
|No averaging of time is involved.
|The concept of crashing is not applied.
|The concept of crashing is applied.
|It is suitable when high precision in time estimates is required.
|It is suitable when reasonable precision is required.
|It lays emphasis on reduction in the execution time of the project without too much cost implications.
|It lays emphasis on the greatest reduction in completion time with the least increase in project cost.
|Previous work experience is not necessary.
|CPM assumes the previous experience with the work necessary.