Difference between PERT and CPM
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CPM and PERT are both scheduling methods that use a common approach to design networks and determine critical paths. PERT focuses on time estimation with uncertainty, using three time estimates per activity, while CPM uses a single estimate and prioritizes time-cost tradeoffs. The key differences between CPM and PERT are that PERT is probabilistic and event-oriented, allows for uncertain durations, and does not allow crashing, while CPM is deterministic, activity-oriented, has known durations, and allows crashing to reduce time.
Difference between PERT and CPM
- 1. The two scheduling methods, uses common approach for designing the network and for ascertaing its critical path. CPM is different from PERT in a way that the former concentrates on time while the latter stresses on time-cost trade-off. In the same manner, there are many differences between PERT and CPM, which we are going to discuss below. Parameters PERT CPM Basic Concept A Probabilistic model with uncertainty in activity duration. Expected duration is calculated from to, tm, tp A deterministic model with well known activity duration based upon past experience Estimates Three time estimates (optimistic time, most likely time and pessimistic time) Single time estimates Orientation Network is constructed on the basis of Events (Event oriented) Network is constructed on the basis of jobs or Activities (Activity oriented) Nature of job Non repetitive nature Exp: Research and development project, Defence project Repetitive nature Exp: Civil construction, industrial setting, plant maintenance, Ship building Focuses on Time (meeting time target or estimating percent completion is more important. Resources are always made available as and when required) Time-Cost trade off (Optimising cost is more important. there is better utilisation of resources) Crashing Not Possible (as there is no certainty of time activity duration cannot be reduced Possible