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PERT is called program evaluation and review techniques and CPM stands for Critical Path Method. The Longest activity duration while preparing schedule and activity list; in a project is called critical path. PERT is a six step process. Steps one and two begin with the project manager laying out a list of activities to be performed and then placing these activities in order of precedence, thus identifying the interrelationship. These charts drawn by the project manager are called logiccharts, arrow diagrams, work flow or simply networks. Step three is reviewing the arrow diagrams with the line managers in order to obtain their assurance that neither too many nor too few activities are identified nor the interrelationship is correct.
In Step 4 the functional manager converts the arrow diagram to a PERT chart by identifying the time duration for each activity. It should be noted here that the time estimates that the line managers provide are based on the assumption of unlimited resources because the calendar dates have not yet been identified. Step five is the first iteration on the critical path. It is here that the project manager looks at the critical calendar dates in the definition of the project’s requirements. If the critical path does not satisfy the calendar requirements, then the project manager must try to shorten the critical path methods of calculation or asking the line managers to take the “fat” out of their estimates.
Step six is often the most overlooked step. Here the project manager places calendar dates on each event in the PERT chart, thus converting from planning under limited resources to planning with limited resources. Even though the line manager has given you a time estimate, there is no guarantee that the correct resources will be available when needed. That is why this step is crucial. If the line manager cannot commit to the calendar dates, then rep-planning will be necessary. For this reason customers require that formal project plans and schedule be provided thirty to ninety days after contract award.
Finally, PERT Re-planning should be an ongoing function during project execution. The best project managers always have a rolling wave planning in place. Primary objectives on a schedule are:
