WBS and EVM

By breaking the work into smaller and more manageable work elements, a WBS can be used to integrate the scheduled activities and costs for accomplishing each work package at the lowest level of the WBS. This is essential for developing the resource-loaded schedule that forms the foundation for the EVM performance measurement baseline. Thus, a WBS is an essential part of EVM cost, schedule, and technical monitoring because it provides a consistent framework from which to measure progress. This framework can be used to monitor and control costs based on the original baseline and to track where and why there are differences. In this way, the WBS serves as the common framework for analyzing the original cost estimate and the final cost outcome.

When analysts use cost, schedule, and technical information organized by the WBS hierarchical structure, they can summarize data to provide management valuable information at any phase of the program. Because a WBS addresses the entire program, managers at any level can assess their progress against the cost estimate plan. This helps keep program status current and visible so that risks can be managed or mitigated quickly. Without a WBS, it would be difficult to analyze the root cause of cost, schedule, and technical problems, and to choose the optimum solution to fix them.

The WBS also provides a common thread between EVM and the schedule that allows for further understanding of program cost and schedule variances. When the work is broken down into small pieces, progress can be linked to the schedule for better assessments of cost, technical, schedule, and performance issues. The WBS also enhances program control by tying the contractual work scope to the schedule.