工作分解结构(WBS)的实践标准

CHAPTER 1 – Introduction to the Work Breakdown Structure

1.1 Overview

Successful project management relies on thorough planning to define the project objectives in sufficient detail to support effective management of the project. The Work Breakdown Structure (WBS) provides the foundation for defining work as it relates to project objectives. The WBS also establishes the structure for managing the work to its completion. The remaining sections of this chapter are as follows:

1.2 – Concept

1.3 – Objectives

1.2 Concept

The WBS is used in projects:

?To define the project’s scope of work in terms of deliverables and further decomposition of these deliverables into components. Depending on the decomposition method used, the WBS can also define the project’s life cycle process as well as deliverables appropriate to the project, program, or any higher order entity. This project scope decomposition

balances management’s need for control with an appropriate level of detail.

?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

project scope, dependencies, and risk, as well as budget and schedule progress and

performance.

?As a key input to other project management processes and deliverables.

It is important to note that the WBS clearly articulates the project scope. It is a critical input to other project management processes and deliverables such as activity definitions, project schedule network diagrams, project and program schedules, performance reports, control tools or project organization. Moreover, although the WBS is a key input to these project management processes and deliverables, the WBS cannot, itself, act as a substitute for or represent any of these on its own.

For the purposes of this Practice Standard for Work Breakdown Structures, a project can be defined as internally focused, externally focused, or both. Additionally, deliverables for these projects can take the form of products, services, or results.

Internally focused projects can produce deliverables as inputs to other project steps, other individuals, or other organizations within the company sponsoring the project. Externally focused projects typically produce outputs and deliverables for people or organizations outside the company, 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. It will require updating, however, as additional scope information is developed or made available by more complete analysis of the project work to be performed. 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 and high-quality WBS and put it to work in the course of managing a project, program, or any higher order entity.

1.3 Objectives

The primary objectives of the Practice Standard for Work Breakdown Structures are to provide a common ground for understanding the concepts and benefits of the WBS, and 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 is also a core project management standard that is based on the PMBOK? Guide—Third Edition and is used by other PMI standards.

Practice Standard for Work Breakdown Structures—Second Edition

the

Finally,

although

provides guidance in WBS development, it is not intended to be a tutorial on how to create a WBS.

CHAPTER 2 – Defining the WBS

2.1 Overview

A project is made more manageable by breaking it down into individual components that together are known as a Work Breakdown Structure or WBS. Such a structure defines unique work elements that can be completed independently, and facilitates other project management processes such as estimating, sequencing, resource allocation, assignment of responsibilities, and measurement and control of the project. The WBS represents a clear description of the project’s deliverables, or scope—the “what” of the project. It is not a description of a process or schedule that defines how or when the deliverables will be produced.

This chapter will provide more information regarding WBS terms, concepts, the 100% Rule, and an example of a good WBS in action. The remaining sections of this chapter include:

2.2 – Common Usage of Terms

2.3 – Concept

2.4 – The 100% Rule

2.5 – WBS for Construction of a Bicycle

2.6 – Representations of the WBS

2.7 – Summary

2.2 Common Usage of Terms

A WBS, as defined in the PMBOK? Guide—Third Edition, is: “A deliverable-oriented hierarchical decomposition of the work to be executed by the project team to accomplish the project objectives and create the required deliverables. It organizes and defines the total scope of the project. Each descending level represents an increasingly detailed definition of the project work…” The following terms help clarify this definition:

Work Sustained physical or mental effort, exertion, or exercise of skill to overcome obstacles and achieve an objective. Commonly used to refer to a specific activity,

duty, function, or assignment often being a part or phase of some larger

undertaking; something produced or accomplished by effort, exertion, or exercise

of skill. In this context, work refers to work products or deliverables that are the

result of effort and not to the work activity itself.

Breakdown Division into parts or categories; separation into simpler substances;

decomposition.

Structure Something arranged in a definite pattern of organization.

These definitions imply that a Work Breakdown Structure (WBS) has the following characteristics:

?Supports the definition of all work required to achieve an objective, tangible result.

?Is constructed to illustrate and define the hierarchy of deliverables. This hierarchy is organized into “parent-child” relationships.

?Has an objective or tangible result that is referred to as a deliverable. In a sense, the WBS

can be thought of as a “deliverable” breakdown structure.

Additionally, as noted above, the WBS is a deliverable-oriented hierarchical decomposition of the work to be executed by the project team. It can thus be defined in the following terms:

Deliverable Suitable for or ready for delivery; something that can be provided as the

product of development; for example, “under this contract, the deliverables

include both ...”

Oriented Aligned or positioned with respect to a point or frame of reference; focused toward the concerns and interests of a specific group.

to

various criteria into successive levels or layers.

according

Hierarchical Classified

Decomposition The practice of separating the work to be executed into several simpler

compounds or elements that differ from each other and define the original

scope.

These definitions work together to define the overall role of the WBS, that is, to provide a foundation for the development of project schedules, communications, risk management plans, as well as other key project elements.

Terms

of

2.2.1 Definition

The following definitions represent WBS-related terms as defined by the PMBOK? Guide—Third Edition. These terms—and others listed in the Glossary of this standard—facilitate understanding of the integral role the WBS plays in project management practice. Terms are listed here in alphabetical order.

Activity A component of work performed during the course of a project.

Control Account A management control point where the integration of scope, budget, actual cost, and schedule takes place, and where the measurement of performance will occur. Control accounts are placed at selected management points (specific components at selected levels) of the Work Breakdown Structure. Each control account may include one or more work packages, but each work package may be associated with only one control account. Each control account is associated with a specific single organizational component in the Organizational Breakdown Structure (OBS). Previously called a Cost Account.

Discrete Effort Work effort that is directly identifiable to the completion of specific Work Breakdown Structure components and deliverables, and that can be directly planned and measured. Contrast with apportioned effort.

Level of Effort (LOE)Support-type activity (e.g., seller or customer liaison, project cost accounting, project management, etc.) that does not readily lend itself to measurement of discrete accomplishment. It is generally characterized by a uniform rate of work performance over the period of time determined by the activities supported.

Task A term for work whose meaning and placement within a structured plan for project work varies by the application area, industry, and brand of project management software.

WBS Component An entry in the Work Breakdown Structure that can be at any level. Work Package A deliverable or project work component at the lowest level of each branch of the Work Breakdown Structure. The work package includes the schedule activities and schedule milestones required to complete the work package deliverable or project work component.

The following definition is included to reflect common usage:

WBS Element Any single component of a WBS, for example, a labeled box in a graphic depiction of a WBS, or a text entry in an outline.

2.3 Concept

2.3.1 Overview

The WBS assists project leaders, participants and stakeholders in the development of a clear vision of the end products or outcomes produced by the project and of the overall process by which the project will deliver those outcomes. The WBS divides the project scope into hierarchical, manageable, definable packages of work that balance the control needs of management with an appropriate and effective level of detailed project data. The WBS provides the framework for all deliverables across the project life cycle. The various levels of the WBS also provide support for focusing communication with stakeholders and aid in clearly identifying accountability to a level of detail necessary for effectively managing and controlling the project.

The upper levels of the WBS typically reflect the major deliverable work areas of the project or major phases in the project’s life cycle. These levels also provide logical summary points for assessing team and individual performance, communicating accomplishments, and measuring cost and schedule performance.

The content of the upper levels can vary, depending on the type of project and the industry involved. To avoid confusion and rework, it is often prudent to define the labels for the levels of the WBS prior to its construction. The lower WBS elements provide appropriate focus for scope, schedule development, cost estimating, and resource allocation.

Whenever work is logically structured, easily identifiable, and clearly within the capabilities of individuals, project stakeholders can confidently expect that objectives associated with the work can and will be achieved. The use of a WBS helps ensure the project meets these criteria.

2.3.2 Deliverables

It is important to understand the underlying concept of a deliverable, which is the core of a WBS. The PMBOK? Guide—Third Edition defines a deliverable as:

Any unique and verifiable product, result, or capability to perform a

service that must be produced to complete a process, phase or project.

Often used more narrowly in reference to an external deliverable, which is

a deliverable that is subject to approval by the project sponsor or

customer.

The WBS provides the foundation for subsequently integrating the work package details and deliverables with all other aspects of project initiation, planning, execution, monitoring and control, and closing.

A deliverable-oriented WBS provides many benefits to the project, including the following:

?Better communication to project sponsors, stakeholders, and team members;

?More accurate estimation of tasks, timelines and costs;

?Increased confidence that 100% of the work is included.

The deliverable concept and deliverable orientation of the WBS are integral to understanding the proper definition and use of the WBS and the benefits it provides within the larger context of all project management processes.

2.3.3 Design

A well-designed WBS that presents information at the appropriate level of detail and in formats and structures meaningful to those performing the work is an invaluable tool in project management. It provides a graphical representation or textual outline of the project scope. Here are some roles the WBS plays in supporting clarity for project definition:

WBS:

The

?Decomposes (or disassembles) the overall project scope into deliverables and supports the definition of the work effort required for effective management.

?Clearly and comprehensively defines the scope of the project in terms of deliverables that the project participants and stakeholders can understand.

?Supports documentation of the accountability and responsibility for the various deliverables by having a direct relationship among the WBS elements related to the

Organizational Breakdown Structure (OBS) identified through the Responsibility

Assignment Matrix (RAM).

?Provides a structure for organizing the scope and subsequent information regarding the project’s progress, periodic status, and projected performance for which a project

manager is responsible.

?Supports tracking of problems to their root causes to assist the project manager in identifying and implementing changes necessary to assure desired performance.

2.3.4 Management

The WBS supports effective project management in several ways during the life of a project by: ?Separating the deliverable into its component parts to ensure the project plan matches the approved project scope and will fulfill the overall objectives of the project.

?Supporting the decomposition of project scope into simpler components, providing one of the primary methods for managing complex projects.

?Providing a framework for specifying performance objectives.

?Providing a vehicle for integrating and assessing schedule and cost performance.

?Supporting the planning and assignment of responsibilities.

?Assisting in determining resource requirements such as skills and characteristics.

?Facilitating the reporting and analysis of project progress and status data, including resource allocations, cost estimates, expenditures and performance.

2.3.5 Organizational Perspective

The WBS provides the ability to relate the work defined to the responsible organizational units, subcontractors, or individuals. As the work and organizational responsibilities become more clearly defined, individuals, including subcontractors, are assigned responsibility for accomplishing specific WBS elements within defined budgets and schedules.

2.3.6 WBS Levels

The WBS includes all work to be done by the project leaders, stakeholders, and both internal and external participants, such as team members and subcontractors. The WBS provides a clear statement of the objectives and deliverables of the work to be performed. The depth of a WBS is dependent upon the size and complexity of the project and the level of detail needed to plan and manage it. Most Work Breakdown Structures consist of a multi-level hierarchy describing the entire scope to be accomplished by the primary organization: however, the specific number of levels should be appropriate for effectively managing the project in question.

2.4 The 100% Rule

The 100% Rule (Haugan, 2002) is a core characteristic of the WBS. This rule states that the WBS includes 100% of the work defined by the project scope and captures ALL deliverables—internal, external and interim—in terms of work to be completed, including project management. The 100% Rule is one of the most important elements in the development of the WBS and in the evaluation of the decomposition. The rule applies at all levels within the hierarchy: the sum of the work at the “child” level must equal 100% of the work represented by the “parent”—and the WBS should not include any work that falls outside the actual scope of the project; that is, it cannot include more than 100% of the work.

It is important to remember that the 100% rule also applies at the activity level: the work represented by the activities in each work package must add up to 100% of the work necessary to complete the work package.

2.5 WBS for Construction of a Bicycle

The following sample WBS illustrates key concepts that will be discussed throughout the remaining chapters of this standard.

Figure 2-1 is a sample WBS designed to capture the scope of work required to construct a custom bicycle. To keep the graphic simple, this particular WBS does not differentiate among the many types of bicycles that can be built from similar WBS constructs—a road bike, mountain bike, racing bike or any other—but assumes that detailed requirements for a specific type of bicycle would be provided as further decompositions of the illustrated WBS elements.

This particular example was selected for its simplicity—to enable the reader to focus on the WBS itself, rather than the multitude of alternatives, options, and components required to define a complex, unique, and perhaps esoteric product. The bicycle is a familiar and common product, an example that easily suggests the processes required to produce the end result.

This illustration shows how concepts and guidance described in later chapters work together to produce a “high-quality” WBS that can be used as a foundation for a project that will deliver the desired end product—a completed bicycle that meets the quality, timeliness, feature and functionality requirements of the purchaser.

Specifically, this WBS illustrates the various levels of a WBS, the numbering scheme, naming convention, relationship of parent and child WBS elements, and the representation of each of these characteristics and elements working together to form a complete WBS.

Figure 2-1. WBS Bicycle Example

The bicycle WBS helps to communicate and reinforce some of the concepts presented. The annotated illustration (Figure 2-2) immediately following shows that all WBS elements are not decomposed to the same extent. For example, this hypothetical bicycle WBS does not decompose each level 2 WBS component further into sub-elements. While it can be helpful to decompose the entire WBS to the same level for some projects, there are no hard and fast rules dictating that each WBS element be decomposed to the same level. Decomposition is a use-related characteristic that is defined by the context of the project the WBS is developed to

support. This concept is presented in detail in Chapter 4, Section 4.2.

Figure 2-2. Annotated Bicycle Example

Additionally, this example communicates WBS concepts that reflect application in a broad array of industries. The construction of the WBS can remain the same, such as the relationship of the elements, the decomposition level, and the relationship to other WBS elements. The content of the elements can be modified to reflect the application of the concept in other terms for other industries. This is illustrated in the decomposed elements that lie beneath the Level 2 WBS element for “Integration” (WBS element 1.6). In the drawing above, elements 1.6.4.1–1.6.4.3 are called “Component Test,” “Product Test” and “Customer Test,” respectively. In the next example, Figure 2-3, these same elements are entitled “Unit Test,” “System Test” and “Acceptance Test,” showing how the concept of testing is represented in similar fashion using

basic WBS elements.

Figure 2-3. WBS Example

Finally, throughout the standard, the bicycle WBS is repeatedly used as a reference point to clarify and illustrate concepts. To illuminate the concept being discussed, parts of the WBS are extracted, elements are singled out, or sets of decomposed elements are highlighted by placing dotted lines around them. For clarity, these WBS elements are frequently shown in a number of different representations.

2.6 Representations of the WBS

The WBS can be represented in a variety of ways including graphical, outline, and textual view, all of which are valid. Regardless of the method used, these approaches enable a project team to predict and forecast task costs, schedules, resource requirements and allocations more accurately.

Two common methods are the hierarchy diagram and the outline or tabular view.

Figure 2-4. WBS Representations Comparison

2.7 Summary

In summary, the WBS:

?Defines the hierarchy of deliverables.

?Supports the definition of all work required to achieve an end objective or deliverable(s).

?Provides a graphical representation or textual outline of the project scope.

?Provides the framework for all deliverables across the project life cycle.

?Provides a vehicle for integrating and assessing schedule and cost performance.

?Facilitates assignment of resources.

?Facilitates the reporting and analysis of progress and status data.

?Provides a framework for specifying performance objectives.

CHAPTER 3 – The Importance of the WBS

3.1 Overview

Can a project be a success without a WBS? Consider the following. The WBS: ?Defines all the work of the project, and only the work of the project, thereby clarifying the project scope.

?Should be developed by all key project team members to achieve buy-in.

?Provides the baseline for subsequent change control.

?Is a primary input to other project management processes—for example, resource planning, cost estimating, schedule development, and risk identification.

?Provides the framework for project control, performance monitoring, and the foundation for communication with all stakeholders.

?Ensures the work of the project correlates appropriately with the Responsibility Assignment Matrix (RAM) and the Organizational Breakdown Structure (OBS).

?Is referenced in other PMI standards—for example, the PMBOK? Guide—Third Edition and Practice Standard for Earned Value Management (EVM)—as an essential planning deliverable supporting key project management functions.

Challenged and failed projects may be devastating to an organization. Experienced project managers know that there are many things that can go wrong in projects regardless of how successful project managers are in the planning and execution of their work. Project failures, however, can often be traced back to a poorly developed or nonexistent WBS.

A poorly constructed WBS can result, among other things, in the following project stumbling blocks and adverse project outcomes:

?Incomplete project definition leading to ongoing project extensions

?Unclear work assignments, goals, objectives, or deliverables

?Scope creep or unmanageable, frequently changing scope

?Budget overrun

?Missed deadlines on scheduled deliverables, or timeline slippage

?Unusable new product or feature

?Failure to deliver on some elements of project scope.

The remainder of this chapter highlights in more detail the important role the WBS plays in project and program management planning:

3.2 – Integration with PM Processes

3.3 – Relationship to Other Tools

3.4 – WBS Integration and Use by Other Standards

3.5 – Summary

3.2 Integration With PM Processes

The WBS is created in the Create WBS planning process. The WBS also plays an integral role in other PM processes. Examples are shown in the following table:

Table 3-1. Project Management (PM) processes

3.3 Relationship to Other Tools

3.3.1 Project Management Tools

The purpose of the WBS, as a project management tool, is to organize the scope of a project. Higher order scope definition practice such as the program management process can use similar techniques to organize scope. There are many project management tools that use the WBS or its components as input.

Project Charter: The WBS takes the project charter as its starting point. The highest-level element in the WBS should represent the project’s overall end-point product(s), service(s), or outcomes as described in the Project Charter. If the project’s major products cannot be described during the creation of the WBS, then the project management team should examine the charter to determine if it has been sufficiently defined.

Project Scope Statement: The Scope Statement for the project is intended to clearly and succinctly describe what the project is and is not intended to accomplish. The high-level elements in the WBS should match, word-for-word, the nouns used to describe the outcomes of the project in the Scope Statement. If the project management team has difficulty identifying the objects in the Scope Statement and applying them to the high-level WBS elements, the team should carefully examine the Scope Statement to determine if it sufficiently captures all project outcomes and deliverables.

Program and Higher Order WBS: The WBS can be used to show relationships with higher order scope management constructs. For example, program offices are typically established to share tools, techniques, methodologies, and resources in managing one or more collections of related projects as program(s). The project WBS must illustrate a clear understanding of the relationship among highly decomposed work packages within individual projects and program (or higher order) scope definitions. If strategic changes are made, the impact on projects, resources, and budgets can be easily calculated, assuming the project WBS has been constructed correctly in consideration of these higher order factors.

RBS: The Resource Breakdown Structure (RBS) describes the project’s resource organization and can be used in conjunction with the WBS to define work package assignments. The link between work packages and the RBS can be used to verify that all members of the project team have been appropriately assigned work packages, and that all work packages have owners. OBS: The Organizational Breakdown Structure (OBS) is loosely related to the WBS. The OBS depicts the organization hierarchy, allowing the project’s work packages to be related to the performing organizational units. This tool reinforces the guideline that each work package should have a single point of responsibility. The OBS can be a useful tool for project managers in that it clearly demonstrates what a WBS does not; namely, the OBS is organized by people or groups, whereas the WBS is strictly organized by deliverables.

WBS Dictionary: The WBS Dictionary is a key document that accompanies the WBS and carries critical project information. The WBS Dictionary defines, details, and clarifies the

various elements of the WBS to ensure that each component of the WBS is accurately articulated and can be communicated to anyone referencing the WBS. The development of the WBS Dictionary often uncovers ambiguity or other errors in the WBS itself, and results in revisions to the WBS. The WBS Dictionary contains information about each element of the WBS, including a detailed description of the work, deliverables, activities, and milestones associated with each element. The WBS Dictionary might also include an indication of the type and number of resources required and contract control information, such as a charge number or other similar data. Often, a WBS Dictionary will include traceability matrices linking the WBS to other scope control documents such as statements of work or requirements documents.

Project Schedule Network Diagram: The Network Diagram is a sequential arrangement of the work defined by the WBS, and is essential to uncovering project dependencies and risks. The lowest-level elements of the WBS are arranged to show precedence and order. Developing the network diagram often uncovers problems in the WBS—such as incomplete decomposition, the assignment of too much work in an element, or more than one person responsible for an individual WBS element—thus resulting in needed revisions.

Project Schedule: The various elements of the WBS are used as starting points for defining the activities included in the Project Schedule. Implied dependencies can be recorded in the WBS Dictionary, and the activities as described in the WBS Dictionary are then included as detail in the schedule.

Because of interrelationships among the WBS and other project management tools, it is important to note that any change in the WBS requires an associated change in the related tools.

This discussion briefly describes how many project management tools are interrelated, all based upon the foundation of the WBS. The Work Breakdown Structure plays an integral role in project and program management, from the Initiating and Planning phases through

Monitoring/Controlling and Executing.

Such interrelationships among the WBS and other Project Management processes are described throughout the PMBOK? Guide—Third Edition. As an example of these interdependencies, consider the relationship between the WBS and the activity list used for the project schedule as described in Section 6.1.2 of the PMBOK? Guide (Activity Definition: Tools and Techniques). Specifically, item 6.1.2.1 (Decomposition) reads:

“The technique of decomposition, as it is applied to activity definition,

involves subdividing the project work packages into smaller, more

manageable components called schedule activities. The Activity

Definition process defines the final outputs as schedule activities rather

than as deliverables, as is done in the Create WBS process (Section 5.3).”

“The activity list, WBS, and WBS dictionary can be developed either

sequentially or concurrently, with the WBS and WBS dictionary being the

basis for development of the final activity list. Each work package within

the WBS is decomposed into the schedule activities required to produce

the work package deliverables. This activity definition is often performed

by the project team members responsible for the work package.”

Section 6.2 of the PMBOK? Guide (Activity Sequencing) further states:

“Activity sequencing involves identifying and documenting the logical

precedence relationships among schedule activities. Schedule activities

can be logically sequenced with proper precedence relationships, as well

as leads and lags to support later development of a realistic and achievable

schedule.”

3.3.2 WBS Development Tools

There are a number of project management tools that can be used to assist a project manager with the development of a WBS. These tools include outlines and organization charts, fishbone and brainstorming techniques, and top down and bottom up development strategies. There are many WBS templates available, and corporate standards can be referenced or copied for quick-starting WBS development. (More information about these tools can be found in Chapter 5 of this WBS Practice Standard.)

There are many benefits to using tools to develop a WBS. For example, tools often promote consistency and repeatability in the development of a WBS, especially enterprise productivity tools. WBS tools can also promote and enforce the principles of the WBS standard and can significantly reduce the development effort, simplifying the WBS process, and even promoting reusable WBS products.

3.4 WBS Integration and Use by Other Standards Similar to the WBS Practice Standard, there are other project and program management standards to which the issue of project scope is central and integral. PMI standards where scope is important include, but are not limited to: the PMBOK? Guide—Third Edition; Practice Standard for Scheduling, Practice Standard for Earned Value Management (EVM), and Organizational Project Management Maturity Model (OPM3?). Therefore, the successful application of these standards depends, in part, on the effective application of this WBS Practice Standard. Moreover, the development of a quality WBS is critical to successful execution of project management processes, as described in the PMBOK? Guide—Third Edition,as well as in the other aforementioned standards.

Standards that take advantage of the WBS typically fall into one of two categories. The first category focuses on using the content output of the WBS as an input. PMI’s Scheduling and Earned Value Management (EVM) practice standards fall into this category. Since the content output from a WBS is predictable and well understood, such standards can build upon or leverage the WBS Practice Standard.

Other standards incorporate the WBS (as defined by this practice standard) as the preferred technique to develop the scope definition for their role. For example, the PMBOK? Guide—Third Edition uses the WBS Practice Standard to develop the project scope, and OPM3 identifies

the WBS as a tool that can be used to develop a program WBS. These standards recognize the WBS Practice Standard as representing best-in-class practice, and make good use of it, rather than building a competing scope management standard.

Scheduling: The WBS is developed to define carefully what is in the project scope and, by implication, what is out of scope. The Practice Standard for Scheduling is based, in part, on an assumption that a high-quality WBS has been developed using good practice, correctly defining project scope. When the project schedule is developed, each high level (summary) task must correspond to a WBS element. If an activity or task does not have a relationship to a work package within the WBS, then either the WBS does not fully encompass the project scope, or the activity or task is unnecessary.

EVM: EVM is a management methodology for integrating scope, schedule, and resources, and for objectively measuring project performance and progress. The data used in EVM are dependent upon WBS elements having been developed using good practice. If WBS elements are not well defined, are too large in scope, are too lengthy in duration, or are in some other manner not appropriately decomposed or developed, it will be difficult to measure the project’s Earned Value. The Practice Standard for Earned Value Management relies upon a high-quality WBS as a key input.

PMBOK? Guide: The PMBOK? Guide—Third Edition, PMI’s renowned project management standard, discusses all elements of project management practice. A core element of project management is scope management, and the PMBOK? Guide discusses the benefits of using the WBS as a technique to manage and control a project’s scope.

Program Management:The Standard for Program Management describes how collections of related projects are best managed. This standard assumes that the WBS for each relevant project is developed according to good practice and accurately describes the scope for the project. Portfolio Management: The Standard for Portfolio Management describes how collections of projects or programs are best managed. This standard assumes that the WBS for each relevant project/program is developed according to good practice and accurately describes the scope for the project.

OPM3: PMI’s OPM3 is an example of a maturity model that can be used to measure and detail an organization’s maturity level, as well as provide a clear path to higher levels of maturity. The WBS is important to OPM3, since OPM3 relies on the benefits of processes aimed at scope management. This standard relies on the development of a quality WBS as a foundation for effective project management.

3.5 Summary

The WBS is a critical element in the planning and execution of a successful project. Many project cost, schedule, and quality failures can be traced directly to flaws in the development of the project’s WBS. It is highly unlikely that a project will be successful without the existence of a quality WBS. In contrast, developing and applying a quality WBS will significantly increase

the likelihood of successful project completion. The next chapter will provide insight into the characteristics and components that make up a high-quality WBS.

工作分解结构(WBS,Work Breakdown Structure)

工作分解结构（Work Breakdown Structure，简称WBS）跟因数分解是一个原理，就是把一个项目，按一定的原则分解，项目分解成任务，任务再分解成一项项工作，再把一项项工作分配到每个人的日常活动中，直到分解不下去为止。 即：项目→任务→工作→日常活动 工作分解结构(WBS,Work Breakdown Structure)，以可交付成果为导向对项目要素进行的分组，它归纳和定义了项目的整个工作范围，每下降一层代表对项目工作的更详细定义。 WBS总是处于计划过程的中心，也是制定进度计划、资源需求、成本预算、风险管理计划和采购计划等的重要基础。WBS同时也是控制项目变更的重要基础。项目范围是由WBS定义的，所以WBS也是一个项目的综合工具。 工作分解结构 [编辑] WBS的主要用途 WBS具有4个主要用途： ?WBS是一个描述思路的规划和设计工具。它帮助项目经理和项目团队确定和有效地管理项目的工作。 ?WBS是一个清晰地表示各项目工作之间的相互联系的结构设计工具。 ?WBS是一个展现项目全貌，详细说明为完成项目所必须完成的各项工作的计划工具。 ?WBS定义了里程碑事件，可以向高级管理层和客户报告项目完成情况，作为项目状况的报告工具。

WBS是面向项目可交付成果的成组的项目元素，这些元素定义和组织该项目的总的工作范围，未在WBS中包括的工作就不属于该项目的范围。WBS每下降一层就代表对项目工作更加详细的定义和描述。项目可交付成果之所以应在项目范围定义过程中进一步被分解为WBS，是因为较好的工作分解可以： ?防止遗漏项目的可交付成果。 ?帮助项目经理关注项目目标和澄清职责。 ?建立可视化的项目可交付成果，以便估算工作量和分配工作。 ?帮助改进时间、成本和资源估计的准确度。 ?帮助项目团队的建立和获得项目人员的承诺。 ?为绩效测量和项目控制定义一个基准。 ?辅助沟通清晰的工作责任。 ?为其他项目计划的制定建立框架。 ?帮助分析项目的最初风险。 [编辑] WBS的种类 1．纲要性工作分解结构（SWBS：Summary WBS） 纲要性工作分解结构是指导性的、战略性的工作分解结构。该分解结构只有上面的三级： 第一级：整个系统即防务装备项目，如：飞机系统、电子系统、导弹系统、军械系统、空间系统和地面车辆系统。 第二级：防务装备项目的重大单元，如航空飞行器、舰船、系统实验和资料等。 第三级：从属于第二级的单元，如机体、推进装置、资料、服务和技术出版物等。 2．项目纲要性工作分解结构（PSWBS，Project SWBS） 项目纲要性工作分解结构是针对某一特定项目，对纲要性工作分解结构进行裁剪得到的工作分解结构。 3．合同工作分解结构（CWBS，Contract WBS） 合同工作分解结构是适用于特定合同或采购活动的完整的工作分解结构。CWBS概括了项目的任务，确定了这些任务与项目的组织机构、技术状态的关系，为项目的性能、技术目标、进度和费用之间的联系，确定了逻辑上的约束框架。合同工作分解结构应与合同规定的层次相一致。合同应指出在合同的哪一级别上进行费用累计。承包商为控制其费用而用到的合同WBS的扩延级，应具有费用累计的追溯能力。 而在其他某些具体的应用领域，常见的其他分解结构主要包括： A、合同工作分解结构（CWBS）——它主要用于定义卖方提供给买方报告的层次，通常不如卖方管理工作使用的工作分解结构（WBS）详细。 B、组织分解结构（OBS）——它用于显示各个工作元素被分配到哪个组织单元。

WBS工作分解结构标准

工作分解结构(WBS)标准 工作分解结构(WorkBreakdownStructureWBS)：以可交付成果为导向对项目要素进行的分组，它归纳和定义了项目的整个工作范围每下降一层代表对项目工作的更详细定义无论在项目管理实践中，还是在项目管理理论中，工作分解结构(WBS)都是最重要的内容。WBS总是处于计划过程的中心，也是制定进度计划、资源需求、成本预算、风险管理计划和采购计划等的重要基础。WBS同时也是控制项目变更的重要基础。项目范围是由WBS定义的，所以WBS 也是一个项目的综合工具。 1.WBS的主要用途：WBS是一个描述思路的规划和设计工具。它帮助项目经理和项目团队确定和有效地管理项目的工作。 1.1 WBS是一个清晰地表示各项目工作之间的相互联系的结构设计工具。 1.2 WBS是一个展现项目全貌，详细说明为完成项目所必须完成的各项工作的计划工具。 1.3 WBS定义了里程碑事件，可以向高级管理层和客户报告项目完成情况，作为项目状况的报告工具。 1.4 WBS防止遗漏项目的可交付成果。 1.5 WBS帮助项目经理关注项目目标和澄清职责。 1.6 WBS建立可视化的项目可交付成果，以便估算工作量和分配工作。 1.7 WBS帮助改进时间、成本和资源估计的准确度。 1.8 WBS帮助项目团队的建立和获得项目人员的承诺。 1.9 WBS为绩效测量和项目控制定义一个基准。 1.10 WBS辅助沟通清晰的工作责任。 1.11 WBS为其他项目计划的制定建立框架。 1.12 WBS帮助分析项目的最初风险。 2.WBS的创建方法：创建WBS是指将复杂的项目分解为一系列明确定义的项目工作并作为随后计划活动的指导文档。WBS的创建方法主要有以下两种： 2.1 类比方法。参考类似项目的WBS创建新项目的WBS。 2.2 自上而下的方法。从项目的目标开始，逐级分解项目工作，直到参与者满意地认为项目工作已经充分地得到定义。该方法由于可以将项目工作定义在适当的细节水平，对于项目工期、成本和资源需求的估计可以比较准确。

WBS有效的工作分解结构

WBS有效的工作分解结构 前言 本文目的是为了满足对WBS概念及应用的全面、系统和实用性阐述的长期需 要。旨在帮助项目经理和项目规划者改善项目结构，有效的启动项目，并在项目的全过程中都把WBS作为规划、控制和沟通的关键工具使用。 本书体现了多年来WBS、新项目的范围界定和计划的发展经历，介绍了已经被大家普遍认可的WBS及其在应用中的一些概念，其中许多更详尽的概念是我提出的。此外还提供了许多例子。 在项目管理中，WBS不是一个新概念，但是它经常被误解，没有得到正确使用，达不到其最大的有效性。像做任何计划一样，WBS的使用也需要训练与思考。开始做一项工作，看上去通常比做一个工作计划要简单些。 本书共分为六章： ●第一章，WBS的概念，定义了主题，简单介绍了WBS概念的历史，定义了一些术语，并明确了在项目管理过程中WBS概念的作用。 ●第二章，WBS逻辑基础，讨论了在有效的WBS开发中应考虑的各个方面的问题。 ●第三章，生命期计划：项目群和阶段，提出每一个生命期阶段都是一个单独的、有自己的WBS的项目。 ●第四章，项目运营中的WBS，阐述了PMBOK?①九大领域中的每一部分与WBS的关系及其应用。 ●第五章，WBS的例子与描述。包括对几个不同类型项目的WBS例子的描述，以及第二章中的WBS基本原理的普遍应用的方法。 ●第六章，WBS原理、步骤和审查表。包括对WBS原理以及推荐给项目经 理用来开发项目的WBS的一系列特定的、注重实效的步骤的总结。 ●PMBOK?是美国项目管理协会的商标，该商标在美国和其他一些国家注册。

第章 WBS概论 本章提供了有关WBS的概念、背景以及WBS在项目管理过程中的地位的一些信息。 项目问题和解决方案 开始一个新的项目就像是要开始写一本书，你已经有了想要写些什么的思路，但还不确定怎样开始。就像许多项目计划者和经理们一样，许多作者发现写大纲通常是一种开始写作的最有效的方法。 大纲既是一种组织材料的方法也是一个写作计划。写大纲有许多方法，尤其是有一种基于研究的方法。一般地，规划一个调查研究或数据收集，并决定每一章要讨论的内容及附录是十分必要的。此外，起草章节、收集一批专家的关键评论、以及与评审证明和出版文件有关的实际步骤等，都是必要的。第5章中有一个简单的以WBS形式写书的大纲的例子。 有这样一个被经常使用的比喻，这是一个古老的问题，问：“你怎样吃掉一头大象？”回答当然是：“一次吃一口。”所以，准备大纲的第一步是对“每一口”进行定义和分类。“每一口”都是很重要的，因为有效的工作是一步一步完成的。对一个项目来说，头脑风暴法能够帮助我们自下而上的定义“每一口咬什么”的活动，或者采用自上而下的“分解”过程将一个项目（或整头大象）细分为几个主要部分（如图1-1所示）。无论用任何方法，目的都是开发一种项目所要进行的工作分解结构。 图1-1 大象分解结构图 显然，大象的每个部分还可以继续分解（细分）。例如，头部可以分解为脸、耳朵、象牙、象鼻，四条腿也可以分别独立识别，身体的各个部位可被确定；尾巴和尾巴上的毛也可以分别确定。项目的WBS结构遵从同一概念。WBS是工作的一个总结，而不是工作本身，工作是构

WBS工作分解结构

W B S工作分解结构 Document serial number【NL89WT-NY98YT-NC8CB-NNUUT-NUT108】

WBS工作分解结构 前言 本文目的是为了满足对WBS概念及应用的全面、系统和实用性阐述的长期需 要。旨在帮助项目经理和项目规划者改善项目结构，有效的启动项目，并在项目的全过程中都把WBS作为规划、控制和沟通的关键工具使用。 本书体现了多年来WBS、新项目的范围界定和计划的发展经历，介绍了已经被大家普遍认可的WBS及其在应用中的一些概念，其中许多更详尽的概念是我提出的。此外还提供了许多例子。 在项目管理中，WBS不是一个新概念，但是它经常被误解，没有得到正确使用，达不到其最大的有效性。像做任何计划一样，WBS的使用也需要训练与思考。开始做一项工作，看上去通常比做一个工作计划要简单些。 本书共分为六章： 第一章，WBS的概念，定义了主题，简单介绍了WBS概念的历史，定义了一些术语，并明确了在项目管理过程中WBS概念的作用。 第二章，WBS逻辑基础，讨论了在有效的WBS开发中应考虑的各个方面的问题。 第三章，生命期计划：项目群和阶段，提出每一个生命期阶段都是一个单独的、有自己的WBS的项目。 第四章，项目运营中的WBS，阐述了PMBOK?①九大领域中的每一部分与WBS 的关系及其应用。 第五章，WBS的例子与描述。包括对几个不同类型项目的WBS例子的描述，以及第二章中的WBS基本原理的普遍应用的方法。 第六章，WBS原理、步骤和审查表。包括对WBS原理以及推荐给项目经理 用来开发项目的WBS的一系列特定的、注重实效的步骤的总结。 PMBOK?是美国项目管理协会的商标，该商标在美国和其他一些国家注册。

WBS工作分解结构

W B S工作分解结构公司标准化编码 [QQX96QT-XQQB89Q8-NQQJ6Q8-MQM9N]

WBS工作分解结构 前言 本文目的是为了满足对WBS概念及应用的全面、系统和实用性阐述的长期需 要。旨在帮助项目经理和项目规划者改善项目结构，有效的启动项目，并在项目的全过程中都把WBS作为规划、控制和沟通的关键工具使用。 本书体现了多年来WBS、新项目的范围界定和计划的发展经历，介绍了已经被大家普遍认可的WBS及其在应用中的一些概念，其中许多更详尽的概念是我提出的。此外还提供了许多例子。 在项目管理中，WBS不是一个新概念，但是它经常被误解，没有得到正确使用，达不到其最大的有效性。像做任何计划一样，WBS的使用也需要训练与思考。开始做一项工作，看上去通常比做一个工作计划要简单些。 本书共分为六章： 第一章，WBS的概念，定义了主题，简单介绍了WBS概念的历史，定义了一些术语，并明确了在项目管理过程中WBS概念的作用。 第二章，WBS逻辑基础，讨论了在有效的WBS开发中应考虑的各个方面的问题。 第三章，生命期计划：项目群和阶段，提出每一个生命期阶段都是一个单独的、有自己的WBS的项目。 第四章，项目运营中的WBS，阐述了PMBOK?①九大领域中的每一部分与WBS 的关系及其应用。 第五章，WBS的例子与描述。包括对几个不同类型项目的WBS例子的描述，以及第二章中的WBS基本原理的普遍应用的方法。 第六章，WBS原理、步骤和审查表。包括对WBS原理以及推荐给项目经理 用来开发项目的WBS的一系列特定的、注重实效的步骤的总结。 PMBOK?是美国项目管理协会的商标，该商标在美国和其他一些国家注册。

工作分解结构(WBS)的实践标准

CHAPTER 1 – Introduction to the Work Breakdown Structure 1.1 Overview Successful project management relies on thorough planning to define the project objectives in sufficient detail to support effective management of the project. The Work Breakdown Structure (WBS) provides the foundation for defining work as it relates to project objectives. The WBS also establishes the structure for managing the work to its completion. The remaining sections of this chapter are as follows: 1.2 – Concept 1.3 – Objectives 1.2 Concept The WBS is used in projects: ?To define the project’s scope of work in terms of deliverables and further decomposition of these deliverables into components. Depending on the decomposition method used, the WBS can also define the project’s life cycle process as well as deliverables appropriate to the project, program, or any higher order entity. This project scope decomposition balances management’s need for control with an appropriate level of detail. ?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 project scope, dependencies, and risk, as well as budget and schedule progress and performance. ?As a key input to other project management processes and deliverables. It is important to note that the WBS clearly articulates the project scope. It is a critical input to other project management processes and deliverables such as activity definitions, project schedule network diagrams, project and program schedules, performance reports, control tools or project organization. Moreover, although the WBS is a key input to these project management processes and deliverables, the WBS cannot, itself, act as a substitute for or represent any of these on its own. For the purposes of this Practice Standard for Work Breakdown Structures, a project can be defined as internally focused, externally focused, or both. Additionally, deliverables for these projects can take the form of products, services, or results. Internally focused projects can produce deliverables as inputs to other project steps, other individuals, or other organizations within the company sponsoring the project. Externally focused projects typically produce outputs and deliverables for people or organizations outside the company, 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.

工作分解结构(WBS)在项目控制中的应用

工作分解结构(WBS)在项目控制中的应 用 WBS的基本概念和一些应用在上面文章已提到过。这里想要介绍的是通过将细分化了的所有项目要素统一编码，使其代码化，WBS还可以充当一个共同的信息交换语言，为项目的所有信息建立一个共同的定义。这样，将所有的要素在一个共同的基础上相关联，在此基础上建立信息系统之间的所有信息沟通。应用WBS作为信息的共同基础的最大优点是，为监控及预测费用、进度、实施不同的项目信息，WBS的应用给所有的项目管理人员提供了一个均可以与之作对比的一致基准，并且在大型项目中，由于参加者众多及人员可能发生的变化，使所用的全部名词对所有的参加者都具有相同意义是很重要的，而WBS 通过代码和代码字典的编制可使这一点得到保证。 1．WBS－－信息沟通的共同基础 在现代大型复杂项目中，一般要涉及大量的资源，涉及许多公司、供货商、承包人等等，有时还会有政府部门的高技术设施或资金投入，因而要求的综合信息和信息沟通的数量往往相当大。这些大项目涉及巨资并历时若干年，因此项目开始进行时设想的项目环境随着项目的进展有时会发生很大的变化，即我们已多次提到的项目早期阶段的不确定性。这就要求所有的有关集团要有一个共同的信息基础，一种各有关集团或用户从项目一开始到最后完成都能用来沟通信息的工具。

这些集团包括：业主、供货商、承包人、项目管理人员、设计人员以及政府有关部门等等。而一个涉及恰当的WBS将能够使这些集团或用户有一个较精确的信息沟通联接器，成为一种相互交流的共同基础，因为WBS具有编码结构及代码字典，利用WBS作为基础来编制预算、进度和描述项目的其他方面能够使所有与项目有关的人员或集团都明了为完成项目所需作的工作以及项目的进程。 2．WBS－－系统综合与控制的手段 我们已经知道，典型的项目控制系统包括进度、费用、会计等不同的子系统。这些子系统在某种程度上都是相互独立的，但是各个系统之间的系统信息转移是不可缺少的，必须将这些子系统很好地综合起来，才能真正达到项目管理的目的。WBS的应用可以提供一个这样的手段。 在WBS的应用中，各个子系统都利用它收集数据，这些系统都是在与WBS有直接联系的代码字典和编码结构的共同基础上来接受信息的。由于WBS代码的应用使所有进入到系统的信息都是通过一个统一的定义方法作出来的，这样就能确保所有收集到的数据能与同一基准相比较，并使项目工程师、会计师以及其他项目管理人员都参照有同样意义的同种信息，这对于项目控制的意义是显而易见的。例如许多项目中的典型问题之一是会计系统和进度控制系统不是采用完全相同的分类或编码，但在一个有组织的共同基础之上对成本和进度作出统一、恰当的解释、分析和预测对于项目的有效管理是非常重要的。此

一个经典婚礼项目中WBS工作分解结构

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