The Schedule Method field specifies the scheduling method currently being used by the project. The two possible values for this field are described below.
Plan and track the project using the traditional Critical Path methodology (CPM). CPM schedules all tasks by analyzing their durations and how each task is related to the previous and next tasks. A sequence of interrelated tasks is called a ”'path”' and the longest path in the project schedule is the critical path. It is “critical” because all tasks on this path must be completed on time in order for the project to finish on time. The critical path defines the duration of the project and the project's finish date.
Plan and track the project using the Critical Chain (Theory of Constraints) methodology. Critical Chain project management is an approach to planning and managing projects that emphasizes the needs of the resources required to complete project tasks. The critical chain is the longest set of dependent activities, which explicitly considers resource availability, to achieve a project goal. Critical Chain project scheduling is different from Critical Path and PERT methods, because all work in a Critical Chain project is scheduled as late as possible in the schedule. Buffers of time are consolidated from safety margins that are removed from individual tasks, pooled together, and made available to an entire chain of tasks to use as necessary. These buffers protect the due dates from task overruns that occur unpredictably during project implementation. A buffer automatically absorbs the effects of late-finishing tasks, so the key to successful Critical Chain project management is correctly sizing and then managing these buffers.
Critical Chain project management requires a different approach to managing projects and evaluating worker performance. Critical Chain projects are managed according to a “relay race” analogy, as opposed to the traditional schedules employed in the Critical Path method. After work on a task chain is started, the management focus is simply to make sure the work is done as fast as possible. Like a relay race, the next runner must be prepared to take off as soon as the current runner hands off the baton, and not attempt to finish the race according to a published schedule. This solves the problem in traditional Critical Path projects where any time gained in one part of the schedule is lost due to waiting for the scheduled time to arrive before starting the next task. Project performance is determined simply by monitoring the utilization of the buffers. Resource contentions are resolved by analyzing the impact of allocation alternatives on buffer utilization.