Critical Path Method (CPM)

Summary

The critical path method (CPM) or critical path analysis, is an important project management approach used to determine the project schedule, based on the duration and relationship of project activities. 

Tasks or activities that are a prerequisite to a given task/activity are referred to as a predecessor. Tasks or activities which follow a prerequisite task/activity are considered a successor to that task/activity.

When combined with lead and lag times (used to define any overlap or delay in duration between tasks, respectively), these logical relationships link activities together to reflect the anticipated timing and duration of a project, relative to interdependent events. While several techniques are available to aid in the development and analysis of complex logical relationships, Planview Enterprise column sets, Gantt charts, and CPM reports meet the needs of the majority of users.

Any gap between a scheduled task and its successor is referred to as float (or slack). In other words, the task has some room to slip without causing a problem. The longest chain of tasks in a project schedule that has no float (meaning that a slippage of any task in that chain will cause a project delay) is referred to as the Critical Path.