In the article, we will cover everything you need to know about Work Breakdown Structure (WBS) for your PMP® exam. This information is a consolidation from the PMBOK® guide.
What is Work Breakdown Structure (WBS)?
Work Breakdown Structure (WBS) is the hierarchical decomposition of the total scope of work on the project.
The top node of the WBS is the deliverable to be accomplished. The project manager must decide upon the best method to divide the project work. The project manager may look at historic projects in the lessons learned database for inspiration.
The WBS must be MECE, or Mutually Exclusive Collectively Exhaustive. In other words, the WBS must include all the work required to complete the deliverable and no task can appear twice.
The WBS breaks the deliverable into its logical components. The lowest level of the WBS is the work packages. PMI recommends work packages to be around 8-80 hours long.
The project manager creates the WBS and assigns the work packages to the appropriate team member. The team member is responsible for completing the work package on time.
What is the difference between a work package and activity?
The individual work packages are decomposed into activities by the team member responsible for delivering the work package. After the WBS is assigned, the team member will decide how the work in the work package is divided and completed. S/he will do all the activities required to complete the work package on time.
Why is a WBS in PMP® important?
Here are the top 6 reasons why it is essential to create a WBS before project execution begins:
- They say, “a picture is worth a thousand words.” Having a visual representation of the total scope may be easier for the team to understand the project deliverables.
- The WBS can tell the project manager what has been completed on the project and what still needs to be completed.
- The WBS is important for cost control. Different branches of the WBS may be associated to different cost control accounts. When the project manager reports on the project status, the executive may wish to see the cost of the entire project broken down by control accounts.
- The work packages of the WBS can easily be assigned to team members. The project team can hold each other accountable to complete the work packages required.
- The WBS can speed up project planning. Historic WBS can be used as templates.
- Creating a WBS can reduce project risk and it is recommended by the PMI.
How do I create WBS?
There are two ways to create a WBS for your project: pictorial or outline.
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Pictorial Method
The the pictorial method, the WBS looks like an organizational chart, except instead of names in the chart there are tasks. The sum of the descending nodes add up to all the tasks in the ascending node.
Having a picture representation of all the tasks can be useful when presenting to executives because it will allow them to “see” what is going on in the project.
It can also be useful when assigning responsibility to team members. Each person can visually see what part of the project they are responsible for and how their part fits in the big picture.
The pictorial WBS is also PMI’s recommended method of creating a WBS. Here is an example of a pictorial WBS:
2. Outline Method
Another method to create a WBS is through the outline method. The outline method looks like a list of bullet points with hierarchy. The sum of the sub-items add up to the item above it.
The outline method is useful when you do not have a lot of time, and need to make a rough sketch of the WBS.
Here is an example of a WBS created with the outline method:
What is the link between WBS and RTM?
RTM is the Requirements Traceability Matrix, and it ensures that all the requirements are met in the deliverable. Each requirement is linked to a component on the WBS. In this way, you can ensure that all of the requirements will be met in your project deliverables.
Here is an example of a RTM:
What is the difference between WBS and WBS dictionary?
The WBS and WBS dictionary work together to define the project scope. Because the WBS is a hierarchy chart, you can’t fit a lot of information into the individual cells. However, you may have additional information about that task that you want your project team to know about. Thus, you will include the extra information in the WBS dictionary, which tells you more about each of the tasks on the WBS.