| Work Breakdown Structure |
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The building blocks of sound project managementThesisThe Work Breakdown Structure (WBS) is fundamental to project execution. When we expend insufficient time and develop inadequate detail on the WBS, the project will yield poor results and we can expect to see last minute identification of critical elements. Not only do some essential items occur late in the process, but we can also expect to see cost over-runs, schedule over-runs, poor quality at delivery, and erosion of project tracking ability—where we do not know where we are at any given time because our road map is defective (or missing).
General descriptionThe first step in generating a WBS is to divide the program/project into cost centers. This ‘cost center’ terminology comes from the U.S. Department of Defense, because a government agency like DoD does not have profit centers per se. ScopeIt can not be overstated, that to generate an adequate level of WBS, the scope of the delivery must be clear. Included in the scope are all activities and products the project is required to deliver. These include documentation, aftermarket support, training and a myriad of other items. Each area has a set of tasks and each task can be broken down to the smallest monitor-able quantum of execution. Without a competent WBS, unaccounted for tasks (but clearly predictable tasks) are lost and usually, to everybody’s surprise, are found at the end of the project, often delaying timely closure of the project.SCOPE and Statement of Work (SOW)Scope is often identified or constrained in a SOW. The SOW establishes the boundaries and activities of the project and spells out in substantial detail the work that is to be done, including all required standards listed (including the quality level expected) and work products, which are defined to include process support (for example, configuration management and project management).WBS and RecyclabilityOrganizations often deliver similar projects (embedded, software etc) and they can reuse any WBS from previous projects as a starting point for the new project. On the downside, there is a risk of recycling earlier problems and not accounting for changes since the last use of the WBS. If we conducted a good post-mortem on previous WBS documents, then we should have already captured the major issues and recorded permanent corrective actions.Generating the WBSWe can solicit expert opinion, follow industry practices, or borrow from standards and regulations. In some cases, the enterprise will have established processes. We also want to capture team member perspectives as well as identified risks which may have an impact on the WBS; that is; we will instigate mitigating actions such as outsourcing, parallel, and duplication of activities. Outsourced activities will require WBS elements from the supplying and customer organizations.Creating the hierarchy of tasksTop level tasks represent areas of costing interest (for example, software development). The decomposition of tasks will follow the way in which the tasks are assembled or go together functionally once we have defined the top level cost centers.Here is a military example (MIL-STD-881B) for electronics development:
Note how the breakdown is logical and accounts for the complete project. MIL-STD-881 provides templates for major programs/projects to provide a good start to new programs. The sub-tasks have progressively smaller durations and are the constituent tasks of upper level tasks. Activity SequencingEach of the building blocks may have interactions and dependencies; for example, we must design hardware before we build hardware. The WBS structure allows for manipulation of the tasks to work through dependencies and risk. The WBS provides enough information to define all required tasks—the project manager will still use a network diagram to represent task dependencies.Duration EstimatesThe smallest size WBS elements have a reasonable chance at accurate estimation due to their small size. The status can be binary (complete, incomplete). This approach has the advantage of eliminating the use of percentages to represent completion status, a technique which our experience shows to be overly optimistic. The small-element approach also makes for easier deployment of estimating techniques such as Program Evaluation and Review Technique (PERT) and Monte Carlo simulation. Figure 2 PERT Time phased budgetThe time-phase budget will include the schedule and cost (usually in hours). This approach is necessary for Earned Value Management (EVM), which includes the following metrics:
Figure 4 Time phased budget detailed resolution Scope controlThe WBS helps to simplify and empower scope control for the project manager. The rules are simple: Task IdentificationTask identification is accomplished through a format know as the WBS dictionary, which—as dictionaries do—defines the meaning and properties of each element of the WBS. Of course, the task must be known beforehand so we can identify expectations, attributes and quality levels for the task. We must also identify resources and processes required to generate the specific WBS element. Quality AssuranceTasks and descriptions of those tasks are used to generate quality assurance activities such as reviews, tests, and inspections. We can also perform a comparison of actual deliverables to the task quality description as a form of auditing—this action is often performed by some person or entity not delivering the task. Task SequencingTo properly identify sequencing, we must understand task dependencies. Additionally, tasks will relate to each other in the form of: How far do we break it down?Based on experience, we suggest that hierarchical task sets should be broken down to the ‘atomic’ level which is the point at which breaking the element down any further makes no sense or becomes silly. This approach helps when using binary reporting (complete, incomplete). Project management software can calculate percentages for upper management based on the roll-up of the binary status of each task. More importantly, it is easy to detect when the project is executing outside of the expected rate of task closure. WBS and ResponsibilityWe assigned WBS elements (tasks) by identifying the responsibility for each delivery/deliverable. We can do this by using a resource allocation matrix, which represents responsibilities and deliverables graphically by matching work with organization breakdown structure (OBS) shown at right angles to the tree/table that represents the WBS. Organizational Breakdown Structure (OBS)An OBS is a similar tree structure to the WBS—effectively an organizational chart of human resources available to the cost centers of the WBS. We use cross-mapping with the WBS to provide a responsibility matrix. The WBS and Work PackagesWork packages are WBS elements. They can be a sub-task or a collection of related tasks. In some cases, the tool helps us to outsource another company’s internal work group. Since the WBS requires substantial definition of each element, the requirements are unequivocally known. The WBS and outsourcingContract work can be outsourced initially with an SOW. Afterwards, we follow up with identification of the WBS for the outsourced activity; we derive this new WBS from the upper level project WBS. The tool helps to provide points for status updates and control. The WBS fine resolution allows quick determination about when things don’t go according to plan and allows for initiation of previously considered risk mitigation activities (we did consider contingency plans already, right?). WBS provides a baselineThe WBS gives us a baseline of activities to achieve the project targets. As we noted already changes to project targets or scope additions have an impact on the WBS. Each change can be reviewed for impact by comparing the original WBS to changes required, again providing for a high level of project control. WBS does / doesn’tThere are some things the WBS can and cannot do. For example, it doesn’t: The WBS does:Supports scope identification / clarification ConclusionWithout task details for the project, success is largely luck and often improbable (the use of the ‘hope’ method of project management). Additionally, the WBS prevents ‘falling through the cracks’ by accounting for everything that must be done.
About the Authors
Project Management of Complex and Embedded Systems: Ensuring Product Integrity and Program Quality
Six Sigma for the Next Millennium: A CSSBB Guidebook Comments (1)
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Kim H Pries APICS: CPIM: ASQ: CQA, CQE, CSSBB, CRE is responsible for all test and evaluation activities and automated test equipment at Stonebridge Electronics-North America. He holds a masters degree and presently teaches the ASQ Six Sigma Black Belt Certification. Kim has written Six Sigma for the Next Millennium A CSSBB Guidebook published by American Society of Quality Publications and co-authored with Jon Quigley the book titled, Project Management of Complex and Embedded Systems: Ensuring Product Integrity and Program Quality, published by Auerbach Publications.
Jon Quigley MBA, M.Sc.PM, PMP, is Manager of Electrical / Electronic Systems and Verification group for Volvo 3P - Product Development North America. He holds two Masters Degrees and is a certified PMP.
