Progress will be measured against the baseline schedule throughout the life of the project. Once established and agreed, the project schedule becomes what is known as the baseline schedule. At this stage, the project schedule may be optimized to achieve the appropriate balance between resource usage and project duration to comply with the project objectives. Then the necessary resources can be estimated and costs for each activity can be allocated to each resource, giving the total project cost. Float or slack time in the schedule can be calculated using project management software. The critical chain method adds "buffers" in the planning to anticipate potential delays in project execution. Therefore, the duration of the tasks is often estimated through a weighted average of optimistic, normal, and pessimistic cases. Project planning is inherently uncertain as it must be done before the project is actually started.
The logical dependencies between tasks are defined using an activity network diagram that enables identification of the critical path. Project planning is often used to organize different areas of a project, including project plans, work loads and the management of teams and individuals. Following this step, the durations for the various tasks necessary to complete the work are listed and grouped into a work breakdown structure. Initially, the project scope is defined and the appropriate methods for completing the project are determined.