Chapter 1
Introduction to the Practice Standard for Work Breakdown Structures—Second Edition
1.1 Overview
Successful project management relies on thorough planning. This begins by defining the project objectives with sufficiently detailed information. The Work Breakdown Structure (WBS) provides the foundation for defining work as it relates to project objectives. The WBS also establishes the framework for managing the work to its completion. The remaining sections of this chapter are as follows:
1.2 Concept
The WBS is used in projects as follows:
- To define the project's scope of work in terms of deliverables and to further decompose these deliverables into components. Depending upon the decomposition method used, the WBS can also define the project's life cycle as well as the deliverables appropriate to the project, program, or portfolio. This project scope decomposition balances management's need for control with representation of an appropriate level of detail in the WBS.
- To provide the project management team with a framework on which to base project status and progress reports.
- To facilitate communication between the project manager and stakeholders throughout the life of the project. The WBS can be used to communicate information regarding the project scope. In combination with additional data, the WBS is the framework for communicating information that includes, but is not limited to, schedule, risk, performance, dependencies, and budget.
- As a key input to other project management processes and deliverables.
The WBS articulates the project scope. It is considered as critical input to other project management processes and deliverables such as activity definitions, project schedule network diagrams, project and program schedules, performance reports, risk analysis and response, control tools, or project organization. Moreover, although the WBS is a key input to these project management processes and deliverables, the WBS is not a substitute for any of these on its own.
For the purposes of this Practice Standard for Work Breakdown Structures—Second Edition, a project can be defined as focused internally, externally, or both. Additionally, deliverables for these projects can take the form of products, services, achievement of specific objectives, or attainment of goals.
Internally focused projects can produce deliverables as inputs to other project phases, other individuals, or other organizations within the organization sponsoring the project. Externally focused projects typically produce deliverables for people or organizations outside the organization, such as customers or project sponsors. Many projects produce both internally and externally focused deliverables. Regardless of the focus of the project, a WBS should be prepared in all cases.
Developing a WBS is an essential step during the initial project phases; as soon as the basic scope has been identified, the initial WBS can be created with limited scope information. As additional scope information is developed or made available by more complete analysis of the project work to be performed, the WBS can be updated through the formal change control processes. This updating process is known as “progressive elaboration.”
This practice standard provides insight into the WBS, its development and its application. It is expected that use of the principles found in this standard will enable the user to prepare a valuable, high-quality WBS and put it to work in the course of managing a project, program, or portfolio.
1.3 Objectives
The primary objectives of the Practice Standard for Work Breakdown Structures—Second Edition are (1) to provide a common ground for understanding the concepts and benefits of the WBS and (2) to present a standard application of the WBS as a project management tool. The intent is to encourage consistency in applying this tool and, as a result, to improve project planning and control. The Practice Standard for Work Breakdown Structures—Second Edition provides guidance in WBS development, based on the PMBOK® Guide—Third Edition, and is used by other PMI standards.
Finally, although the Practice Standard for Work Breakdown Structures—Second Edition provides guidance in WBS development, it is not intended to be a tutorial on how to create a WBS.