In this article, we will look at the difference between PERT and CPM, Their definitions, and how to solve CPM problems and pert problems and, more
The Difference between CPM and PERT has been explained in the following table
Parameter | PERT | CPM |
Definition | Program Evaluation and Review Technique (PERT) is a statistical tool used for project management to analyze and represent the tasks involved in completing a project. | Critical Path Method (CPM) is a project management technique used to identify the critical path in a project and optimize the schedule to minimize the overall duration. |
Focus | PERT focuses on the time required to complete each task and the overall time required to complete the project. | CPM focuses on identifying the critical path and optimizing the schedule to minimize the overall duration. |
Uncertainty | PERT is suitable for projects with a high degree of uncertainty, as it allows for the estimation of task duration based on optimistic, pessimistic, and most likely time estimates. | CPM is suitable for projects with a low degree of uncertainty, as it assumes that the duration of each task is known with certainty. |
Activity relationships | PERT represents activity relationships using probabilistic relationships, such as the expected time, variance, and standard deviation. | CPM represents activity relationships using deterministic relationships, such as the earliest start time, latest start time, and float time. |
Calculation | PERT uses the Expected Time (TE) formula, which is TE = (Optimistic Time + 4 x Most Likely Time + Pessimistic Time) / 6. | CPM uses the Forward Pass and Backward Pass techniques to calculate the earliest start and finish times and latest start and finish times for each activity. |
Focus on critical activities | PERT does not explicitly identify the critical path but focuses on the tasks with the longest expected duration. | CPM explicitly identifies the critical path and focuses on optimizing the schedule to minimize the duration of the critical path. |
Application | PERT is widely used in research and development projects, where there is a high degree of uncertainty and risk. | CPM is widely used in construction and manufacturing projects, where the duration of each task is known with certainty. |
Difference between CPM and PERT?
Difference between CPM and PERT |
Introduction To CPM and PERT:
PERT (Program Evaluation and Review Technique) and CPM (Critical Path Method) are project management tools used to plan, schedule, and control projects. Both techniques help project managers to identify the critical path of a project, which is the sequence of activities that must be completed on time in order to meet the project deadline.
Both PERT and CPM use a network diagram to represent the sequence of activities in a project.
The network diagram shows the activities as nodes and the dependencies between them as arrows.
PERT NETWORK DIAGRAM SAMPLE |
CPM NETWORK DIAGRAM SAMPLE |
PERT and CPM also use a forward and backward pass analysis to calculate the earliest and latest start and finish times for each activity and to identify the critical path.
The critical path is the longest path through the network diagram and represents the minimum amount of time required to complete the project.
Any delay in activities on the critical path will delay the completion of the project.
Project managers can use PERT and CPM to identify the critical path and determine the activities that are most important to complete on time.
Difference between CPM and PERT Explanation in video
How to solve CPM problems with a network diagram
- Network diagram
- Earliest starting time
- Earliest finish time
- Lastest starting time
- Latest finishing time
- Total float
- Free float
- Independent float
How to solve PERT problems with a network diagram
In PERT, there are three-time estimates that are used to calculate the expected duration of each activity. These three-time estimates are:
- Optimistic Time (O): This is the shortest possible time in which an activity can be completed assuming everything goes as planned.
- Most Likely Time (M): This is the best estimate of the time required to complete an activity under normal circumstances.
- Pessimistic Time (P): This is the longest possible time in which an activity can be completed assuming everything goes wrong.
Using these three time estimates, the expected duration of an activity can be calculated using the following formula:
Expected duration (TE) = (O + 4M + P) / 6
The main difference between CPM and PERT
The main difference between PERT and CPM is that
- PERT is a probabilistic tool, while CPM is a deterministic tool.
- PERT allows project managers to account for uncertainty in the duration of activities by using three time estimates (optimistic, most likely, and pessimistic) to calculate the expected duration of each activity. CPM, on the other hand, assumes that the duration of each activity is known with certainty.
Conclusion for Differences between CPM AND PERT
Both PERT and CPM are project management tools that are used to analyze and optimize the schedule of a project.
However, PERT is suitable for projects with a high degree of uncertainty,
while CPM is suitable for projects with a low degree of uncertainty.
PERT focuses on the time required to complete each task and the overall time required to complete the project. In contrast, CPM focuses on identifying the critical path and optimizing the schedule to minimize the overall duration.
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