Critical Path Method (CPM) and PERT Network are used as project management techniques for planning, scheduling, and controlling.
The Framework of both PERT and CPM is similar; they are:
Both PERT and CPM follow six basic steps:
1. Defining the project and preparing the work breakdown structure.
2. Developing the relationships and precedence among the activities.
3. Drawing the network connecting all the activities.
4. Assigning time and cost estimates to each activity.
5. Computing the longest time path through the network. This is called the critical path.
6. Using the network to help plan, schedule, monitor, and control the project.
PERT and CPM provide answers to the following questions related to a project:
1. The time of completion of the entire project
2. The critical activities and tasks in the project. The critical activities are those activities if they are delayed, the entire project will be delayed
3. The non-critical activities.
4. The probability of completion of the project at a specific time
5. Status of the activities of the project during the process; whether the activities are completed on time, behind, or before time.
6. Status of the budget available during the process.
7. Status of resources available during the process.
8. Opportunities to increase efficiency by reducing cost and time.
Difference between PERT and CPM
1. PERT is used to manage uncertain (i.e., time is not known) activities of any project. CPM is used to manage only certain (i.e., time is known) activities of any project.
2. PERT is a probability model, where the expected time of completion of tasks is not determined. CPM is a deterministic model where the expected time of completion of each activity is determined.
3. PERT is suitable for the non-repetitive nature of the job. CPM is suitable for has repetitive nature of the job.
Network Analysis in CPM and PERT
Network analysis is a technique used for the management of projects. Network systems are used in PERT and CPM to graphically depict the current problems or proposed projects. A network diagram depicts activities and inter-dependencies and the precedence relationship of these activities with other activities. A network includes Activities and Events.
What is 'Activity' in a network diagram:
Activity is any single operation that needs resources and has a beginning and an end. Activity is depicted with an arrow to indicate the direction of the progress in the project.
According to the position of activity, it can be called:
a) Predecessor activity: an activity that must be finished to the start of another activity.
b) Successor activity: an activity that cannot be started until other activities are finished, then immediately succeed the previous activity.
What is 'Event' in a network diagram:
Event is the beginning and endpoints of an activity. The event is also called Node or Connector.
What is the difference between event and activity?
An event is that particular instant of time at which some specific part of the project is to be completed.
An activity is an actual performance that requires time and resources for its completion.
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