According to the PMBOK® Guide, specifically the Develop Schedule process, the Critical Path Method (CPM) is a fundamental technique used to estimate the minimum project duration and determine the amount of scheduling flexibility on the logical network paths within the schedule model.
The Definition of Critical Path: The critical path is defined as the sequence of activities that represents the longest path through a project, which determines the shortest possible duration to complete the project.
Total Float (Slack): Activities on the critical path typically have zero float. This means any delay to an activity on this path will directly delay the project completion date.
Logical Network Analysis: To determine the critical path, the project manager performs a " Forward Pass " to calculate the earliest start and finish dates, and a " Backward Pass " to calculate the latest start and finish dates. The path where these dates are the same (Zero Float) is the critical path.
Dynamic Nature: A project can have multiple critical paths, and the critical path can change throughout the project as activities are completed earlier or later than planned.
Analysis of other options:
Option A: Crashing is a schedule compression technique used to shorten the duration for the least incremental cost. While it involves the critical path, the definition of the critical path itself is not " the crashed schedule. "
Option C: Tasks with float (or slack) are specifically not on the critical path. Identifying them helps you understand where you have flexibility, but it does not define the critical path itself.
Option D: Resource Leveling is a technique used to adjust the schedule based on resource constraints. While leveling can change the critical path (often resulting in a " Critical Chain " ), the standard definition of a critical path is based on the sequence of activities, not the leveled resource state.
Per PMI standards, the critical path is the sequence of dependent tasks that forms the longest duration path, thereby establishing the earliest possible date the project can be finished.
