The PMP Certification Exam will have questions about the critical path method. Critical path — the most common form of teaching scheduling — is the method that most software employs. The critical path method determines the date ranges in which activities occur by calculating the earliest and latest dates when activities can start and then the earliest and the latest dates when activities can finish based on the network diagram and duration.
Most critical path analyses are done prior to loading resource availability into the schedule. After resources are loaded, the duration of the project can change. The critical path method has several terms you need to be familiar with.
Critical path method (CPM). A method used to estimate the minimum project duration and determine the amount of scheduling flexibility on the logical network paths within the schedule model.
Early start date (ES). In the critical path method, the earliest possible point in time when the uncompleted portions of a schedule activity can start, based on the schedule network logic, the data date, and any schedule constraints.
Early finish date (EF). In the critical path method, the earliest possible point in time when the uncompleted portions of a schedule activity can finish, based on the schedule network logic, the data date, and any schedule constraints.
Late finish date (LF). In the critical path method, the latest possible point in time when the uncompleted portions of a schedule activity can finish based on the schedule network logic, the project completion date, and any schedule constraints.
Late start date (LS). In the critical path method, the latest possible point in time when the uncompleted portions of a schedule activity can start based on the schedule network logic, the project completion date, and any schedule constraints.
Total float. The amount of time that a schedule activity can be delayed or extended from its early start date without delaying the project finish date or violating a schedule constraint.
Free float. The amount of time a schedule activity can be delayed without delaying the early start date of any successor or violating a schedule constraint.
Forward pass. A critical path method technique for calculating the early start and early finish dates by working forward through the schedule model from the project start date or a given point in time.
Backward pass. A critical path method technique for calculating the late start and late finish dates by working backward through the schedule model from the project end date.
Critical path. The sequence of activities that represents the longest path through a project, which determines the shortest possible duration.
Here are the steps to analyze the schedule, using the critical path method:
Draw the network diagram.
Box the network diagram.
Enter durations into the diagram.
Conduct a forward pass.
Conduct a backward pass.
Calculate float.
Identify the critical path.
