Project Planning and Control

Difference Between PERT and CPM

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

1The origin of PERT is defence (navy)The origin of CPM is industry (Chemical Plant)
2It is event an oriented approach.It is an activity oriented system.
3There is allowance for uncertainty.It does allow not any uncertainity.
4It is a probabilistic model with uncertainty in activity duration.It is a deterministic model with well known activity time based past on experiences.
5It is time based.It is cost based.
6It does not demarcate between critical and non-critical events.It marks critical activities.
7Time is averaged in it.No averaging of time is involved.
8The concept of crashing is not applied.The concept of crashing is applied.
9It is suitable when high precision in time estimates is required.It is suitable when reasonable precision is required.
10It 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. 
11Previous work experience is not necessary.CPM assumes the previous experience with the work necessary.

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