Work Breakdown Structure

From PEaM

PMI	A Work Breakdown Structure (WBS) [PMI Output/Input] is a deliverable-oriented hierarchical decomposition of the work to be executed by the project team to accomplish the project objectives and creates the required deliverables. It organizes and defines the total scope of the project.[1]

DAU

A Work Breakdown Structure is a product-oriented family tree division of hardware, software, services, and other work tasks which organizes, defines, and graphically displays the product to be produced as well as the work to be accomplished to achieve the specified product:[2] Project summary Work Breakdown Structure (PWBS) A summary Work Breakdown Structure (WBS) tailored to a specific defense material item by selecting applicable elements from one or more summary WBSs or by adding equivalent elements unique to the project in accordance with MIL-HNDBK 881 (latest revision) Contract Work Breakdown Structure (CWBS) The complete WBS for a contract, developed and used by a contractor within the guidelines of MIL-HNDBK 881 (latest revision) and according to the contract's work statement. The CWBS includes the levels specified in the contract and the contractor's extension.

Contents 1 Characteristics of a WBS 1.1 Common principles[3] 1.2 100% rule 2 See also 3 References

Characteristics of a WBS

Common principles^[3]

• The WBS covers the total scope of the project. Work not in the WBS is not in the project.
• All deliverables or output products are represented in the WBS.
• The sum of the elements at each level represents 100 percent of the work of the next higher level. (The sum of the Level 2 items is 100 percent of the project work or cost.)
• Work in each element is equivalent to the sum of the work in the subordinate elements.
• The subdivisions should be logical and reflect the nature of the product, service, or result.
• Each WBS element should represent a discrete element of work that can be described in the WBS dictionary.
• Each WBS element should have a unique identifier.
• WBS element descriptors preferably should be nouns, with adjective modifiers if necessary. For clarity or for cultural reasons, WBS descriptors may include verbs and modifiers. However, they should not be considered activities since activities are by definition the action elements that occur below the WBS.
• The work in each WBS element may be described in detail in a WBS dictionary, which may become the basis for statements of work or work-authorizing documents.
• Project management is a Level 2 element in all WBSs.
• Stakeholders should participate in the development of the WBS.
• The WBS should be baselined after approval by the stakeholders.
• A formal change process should exist for baselined WBSs.
• The WBS should focus on project output or deliverables; it is not an organization chart, a schedule, or a resource list.
• The lowest level should be the level above the activities—the work package level.
• The lowest level should permit adequate control and visibility for project management.
• The lowest level need not be the same for all branches of the WBS.
• The lowest level should not be so detailed as to create an administrative burden.
• The WBS does not reflect time relationships or horizontal relationships between elements; all structural relationships are vertical.

100% rule

The 100% rule states that each level decomposition of a WBS element (child level) must represent 100 percent of the work applicable to the next higher (parent) element.

The following questions are asked at each level:

• Does the sum of the work represented by the child elements equal 100 percent of the effort summarized in each parent element?
• Is any work missing?

Experience has indicated that asking these questions invariably results in additional activities being added, and several iterations of the WBS structure may be performed until a sound WBS is developed.

The importance of the 100 percent rule cannot be overstated in the use of the WBS as a framework for planning. If the decomposition at each level follows the 100 percent rule down to the activities, then 100 percent of the relevant activities will have been identified when it is time to prepare the project schedule. And 100 percent of the costs or resource requirements will be identified in the planning phase.^[3]

See also

• Work package
• Control account
• Contract Work Breakdown Structure
• Project summary Work Breakdown Structure

References

1. ↑ Project Management Institute (2008). A Guide to The Project Management Body of Knowledge, 4th, Project Management Institute.
2. ↑ Defense Acquisition University (2005). Defense Acquisition Acronyms and Terms Glossary, 12th, Defense Acquisition University.
3. ↑ ^{3.0 3.1} Haugan, Gregory T. (2003). “Chapter 2 - Work Breakdown Structure Fundamentals”, The Work Breakdown Structure in Government Contracting. Management Concepts.

This article contains text from the Project Management Institute PM Body of Knowledge which is copyright all rights reserved by Project Management Institute, Inc. (PMI). Project Management Body of Knowledge is a registered trademark of PMI

This article contains text from the Defense Acquisition University website which, as a US government publication, is in the public domain.