You can start developing the project work breakdown structure after the project sponsor has defined the project’s scope and major deliverables. You can’t start work on the project work breakdown structure (WBS) until you have that data because that is the starting point for the WBS. You also need the scope and major deliverables defined by a metric; a number that tells you how you’ll measure the results. As an example, let’s say you’re doing a project to reduce the noise in a workspace. The sponsor might define success as, “The average decibel rating of the workspace is 64 dB.” That gives you a metric to use. You will break that down into its major deliverables and then break each of those down into smaller deliverables down to the level of individual team member assignments. Let’s look at how to do this some step-by-step.
Steps in Building a Project Work Breakdown Structure
Project Work Breakdown Structure – Step 1. Break down the scope into the project’s high-level deliverables. You start building the project work breakdown structure by decomposing or breaking down the scope into 4 to 7 high-level project deliverables. Each of those deliverables is defined with a metric, which is an acceptance criterion for the deliverable. As part of our plan you define the way you will measure the acceptability of the deliverables. Here are some examples of high-level deliverables from different projects:
- A. Payroll data entry operators can enter 60 transactions/hour with 99.5% accuracy. This high-level deliverable will be produced by system programmers and analysts. But you are measuring the acceptability of the work productivity of the people who use the system.
- B. The ambient temperature in the grocery store is between 71° and 73° 99% of the time. This high-level deliverable will be assigned to a heating and ventilating subcontractor. You will measure that subcontractor’s work by the HVAC system’s ability to meet the specified metric.
- C. Attendees at a payroll training class score 82% or higher on a test at the end of class. This high-level deliverable will be produced by the company’s trainers. You will measure the trainers’ work on how well the attendees know the new payroll procedures, based on the attendees’ test results.
- D. Sales of a model J-27 device exceed $425,000 in the first 60 days after launch. This is a deliverable that sales will produce in combination with advertising. You will measure their work by the sales figures for that time period.
Sometimes you can work on all of the high-level deliverables simultaneously. In other projects, you will work on them sequentially That means the first deliverable must be completed before you can start work on the second deliverable.
Project Work Breakdown Structure – Step 2. Break down the high-level deliverables into supporting deliverables. You take each high-level deliverable and break it down into the supporting deliverables that are necessary to produce it. As an example, the high-level deliverable described in “A” above – “Payroll data entry operators can enter 60 transactions/hour with 99.5% accuracy” – might be decomposed into several supporting sub-deliverables like:
a. User management approves systems design and acceptance criteria
b. System analysts’ design meets company IT standards and is approved by quality assurance
c. Programmers’ code is accepted by the IT analyst
d. In user testing, data entry operators can enter 60 transactions per hour with 99.5% accuracy.
The training class deliverable described in “C” above may require the following supporting sub-deliverables:
a. User managers approve training class curriculum
b. User managers approve final examination for attendees
c. Training department management approves the course design, training slides and lecture notes for the trainers’ use
d. Payroll processor pilot group has an 88% pass rate on the examination (the pilot passing rate is higher than the high-level deliverable).
You’ll note that some of these sub-deliverables have metrics (numbers) and that is the best kind of acceptance criteria. However, in some design tasks we can’t specify a number. So we use the approval or acceptance by an authorized person or group to measure the success of the sub-deliverable.
Project Work Breakdown Structure – Step 3. Break down the supporting deliverables to the level of individual team member assignments. You continue to break down the supporting deliverables into their components until you reach assignments that you can assign to an individual. Typically, project task assignments should have a duration of between three and ten days. You will give new employees or trainees assignments at the low end of that range. Experienced professionals or experts will be given assignments at the high-end of that range. But every assignment should have a metric or other measure of the acceptability of the deliverable. The reason this is so important is that team members need to know what is expected of them and how their deliverable will be measured before they start work.
Project Work Breakdown Structure – Step 4. In addition to the hierarchy of deliverables, the project work breakdown structure can also contain milestones. These are fixed dates by which certain components of the project have to be completed. You should not use milestones to set your target completion dates because the scheduling software will calculate those. You use milestones to indicate things like external dates that are legally mandated or required by government regulation.
Project Work Breakdown Structure – Step 5. The final step in building a professional-grade project work breakdown structure is to develop the assignment work packages. Usually you will work with the person who is going to produce the deliverable to finalize the details of their assignment. The work package contains information about the deliverable and its associated metric. It has information about the approach the team member will take to produce the deliverable. It also includes procedural and documentation standards that must be met as the deliverable is produced. Finally, you use the work package to document the team member’s work estimate. The “best practice” estimating technique is three-point estimating. It gives the team member the opportunity to reflect the risk of the task in the estimate. Once the estimate is complete, the work package is the contract between the project manager and the team member. It specifies what is going to be produced, how long it should take and how much it should cost.
The work breakdown structure accomplishes a number of critically important things for the project. Specifically, the entries in your project work breakdown structure are:
1. The assignments for each of the team members which specify exactly what they’re supposed deliver
2. The basis for your estimates of duration and cost. Accuracy in those estimates is another reason why you must be crystal clear about what is expected
3. The bench marks you will use to measure and report on progress.