Work Break-down Structure (WBS)

WBS:-
Concept of WBS is developed with PERT(Program Evaluation and Review Technique). Work break down structure can be considered as foundation for project planning. PMBOK defines WBS as "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."
Purpose: - Why do we need WBS?
1. The WBS organizes and defines the total scope of the project
2.WBS helps in assigning responsibilities, resource allocation, monitoring the project, and controlling the project.
3.WBS helps in detailed cost estimating and control along with providing guidance for schedule development and control.
Process to create WBS: - The WBS subdivides project work into smaller, more manageable pieces of work, with each descending level of the WBS representing an increasingly detailed definition of the project work.PMI provide some guidelines:
100% rule :"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 to the activity level." In practice WBS captures only 90-95 work. There are lots of managerial tasks that have to perform to get work done.
8/80 rule for WBS: No work package should be less than 8 hours or more than 80 hours.
WBS can be created by breaking project work using criteria's like:
Functional or technological disciplines. (marketing/legal/admin/development/testing)Vendor/Subcontractor responsibilities.
Physical locations.
System/Subsystems.
As per PMBOK inputs required for creating WBS:
Organizational Process Assets: Organizational process assets are the formal and informal policies, procedures, and guidelines.
Project Scope Statement : The project scope statement describes the projects deliverables and the work required to create those deliverables.
Scope Management Plan: Guidelines for how scope is to be managed and how scope changes are to be integrated into the project.
Approved Change Requests: Approved change request should be include in WBS.
Along with these inputs your project team is very important for creating WBS.
Tools/techniques to create WBS:
Work Breakdown Structure Templates: Although each project is unique, a WBS from a previous project can often be used as a template for a new project, since some projects will resemble another prior project to some extent.
Decomposition : Decomposition is the subdivision of project deliverables into smaller, more manageable components until the work and deliverables are defined to the work package level. The work package level is the lowest level in the WBS, and is the point at which the cost and schedule for the work can be reliably estimated.
Decomposition of the total project work generally involves the following activities:
Identifying the deliverables and related work
Structuring and organizing the WBS
Decomposing the upper WBS levels into lower level detailed components
Developing and assigning identification codes to the WBS components
Verifying that the degree of decomposition of the work is necessary and sufficient.
Post-it technique: Write each deliverable on a post-it note and stick them at the top of a wall. Then you and your team start to break down each deliverable into components and write each component on its own post-it note. This way, as you place them on the wall and start to create your tree structure, everyone can easily see what has been accomplished and where you are headed. Also this technique allows for easy movement of components around within the WBS.
Pitfalls and misconceptions:
Level of work package detail: The To Do list approach to WBS construction belief that the WBS is actually a step-by-step procedure for doing everything. Ultimately this leads to micro-management, which is not generally attractive to team members. If work package is too large it also becomes difficult to handle. So use 8:80 rule.
Task Approach: Your WBS should be list of deliverables and should not list of activities or task. Tasks and activities can vary and change throughout the project, but deliverables cannot without a change request, so you do not want to list activities and tasks in the WBS.
WBS as Plan:The WBS should not be used as a replacement for the project plan or schedule. It is considered poor practice to construct a project schedule before designing a proper WBS.