Chapter 7: Step 4: Determine the Estimating Structure - Work Breakdown Structure

A work breakdown structure (WBS) deconstructs a program’s end product into smaller specific elements that are suitable for management control. The WBS is the cornerstone of every program because it defines in detail the work necessary to accomplish a program’s objectives. The WBS provides a consistent framework for planning and assigning responsibility for the work, and is an essential element for identifying activities in a program’s integrated master schedule. The WBS is initially set up when a program is established and becomes successively detailed over time as more information becomes known about the program. Establishing a product-oriented WBS is a best practice because it allows a program to track cost and schedule by defined deliverables, such as a hardware or software component.

A WBS provides a basic framework for a variety of related activities including estimating costs, developing schedules, identifying resources, and determining where risks may occur. It also provides the framework to develop a schedule and cost plan that can easily track technical accomplishments—in terms of resources spent in relation to the plan, as well as completion of activities—enabling quick identification of cost and schedule variances.