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You will need to know techniques for creating a WBS for the PMP Certification Exam. Decomposition and expert judgment are the only techniques used in developing the WBS. Here is the PMBOK Guide definition of decomposition.

Decomposition. A technique used for dividing and subdividing the project scope and project deliverables into smaller, more manageable parts.

The PMP Examination Outline uses the term deconstruct. The PMBOK Guide uses the term decompose. They mean the same thing.

Expert judgment comes into play when project teams decompose the WBS by starting with the highest level, which is the project. The next level down is how you will organize the project. Many technology projects use the project life cycle as the next level down. However, that’s certainly not the only way to organize the WBS, and perhaps not even the best way.

Other options include major deliverables or geography. After this level is established, it’s just a matter of taking each high-level element and decomposing it into finer levels of detail. The most common is a top-down approach.

The converse approach is a bottom-up approach, which starts with the lowest level of deliverables and works up the chart to see where deliverables naturally group themselves.

The lowest level of the WBS is called a work package, which is the level where duration and cost can be estimated reliably.

Because the WBS represents all the work in the project, you must make sure you aren’t overlooking anything! Sometimes people forget to put in “project management.” If you need a WBS to reliably estimate cost and duration, you will significantly underestimate if you leave out the project management deliverables!

You can put project management as a box in the second level down. And, this is the only branch of the WBS where you might not constrain yourself to identifying deliverables only. So much of your job is action-oriented that you might put an entry such as stakeholder management, or communication, or change management. Another option is to put the process groups under project management.

The work package is the lowest level of the WBS, but reporting progress at the work package level is probably too detailed. A large project has hundreds of work packages. You can’t report cost and schedule status for each one and then expect the sponsor or steering committee to read your report! Instead, you establish control accounts, which are where you can reasonably report progress.

A control account encompasses the work packages beneath it and can have multiple work packages. Looking at it from the other side, each work package can belong to only one control account. Here are the definitions for work packages and control accounts.

Work package. The work defined at the lowest level of the work breakdown structure for which cost and duration can be estimated and managed.

Control account. A management control point where scope, budget, actual cost, and schedule are integrated and compared to earned value for performance measurement.

You might not be able to define all the deliverables in the WBS at the start of the project. Commonly, the WBS is established at a high level at the start of the project, and as more information is known, the levels are further decomposed. This is an example of progressive elaboration known as rolling wave planning.

Rolling wave planning provides more detail for work happening in the near future, but leaves work further out in the future at a higher level. This doesn’t mean you don’t have to account for the cost and schedule for future work; you just hold it at a higher level of detail until you know what the lower level of detail looks like.

This WBS is arranged by phases at level 2 along with project management. You can see that the earlier work in the project is decomposed to a lower level than the work later in the project (construction, operational readiness), demonstrating rolling wave planning.


Because the WBS is deliverable-oriented, it comprises nouns, not verbs. Many people have difficulty thinking in terms of deliverables instead of actions. With practice, it gets easier: Just think in terms of nouns.

Deliverable Verb Comment
Playground equipment Install playground equipment “Install” implies action. On the WBS, you want only the deliverable.
Curriculum plan Plan curriculum Where you place the terms changes the deliverable from a noun to a verb.

You can arrange your WBS with the project at the top level and deconstruct it downward, or you can deconstruct from left to right.

Not all branches of the WBS can be decomposed to the same level. Some work might stay at three levels because that level is where the deliverables are. Other branches might be decomposed five or six levels.

How low should you go on a WBS? The answer is, “That depends.” For a very large project, a work package might represent $1 million worth of work. For a small project, it might represent $25,000 worth of work, or even less.

When your WBS becomes fairly robust, you should develop a numeric coding structure to keep track of the levels. The first level is 1.0. At the second level, you would have 1.1, 1.2, 1.3, and so on. The third level would have 1.1.1, 1.1.2, 1.1.3, and then 1.2.1. 1.2.2, and so on. Many organizations that do large projects already have a coding structure as part of their organizational process assets.

To make it easier to remember, look at these steps:

  1. Analyze the scope statement and requirements to understand the project work.

  2. Determine how you will structure the WBS (by major deliverable, sub-project, phase, and so on).

  3. Decompose the work until you have work packages or until you can’t realistically decompose it into deliverables.

  4. Identify control accounts for reporting purposes.

  5. Establish a numeric coding structure.

  6. Verify that your WBS is well organized and decomposed to an appropriate level.

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