• The scope of the project in its inherent sense is the work, that must be done to met the required targets, not the targets themselves (which might be given as descriptions of features of a product). Therefore, the Work Breakdown Structure is a tree of tasks and subtasks, not a tree of parts and subparts of a product.
• There is a strong view of the WBS and a weak one: The decomposition should be complete in the sense, that all necessary details will be represented in the task-tree and that what is not in the tree is not in the project scope (strong). On ther other hand: Activity definition is the decomposition of a work package. Hence some 'working steps' are not part of the WBS (weak). The solution of this contradiction lies in the doing of th project manager.
• It is up the project manager to find "a balance between to little and to much in the level of WBS planning detail", although the real act of breaking down the tasks should be done by the domain experts (comp. PMBOK3, pp. 114f)
(2.3) Erstellen des Projektstrukturplans (WBS)
(2.3.1) Process Input
... generated by predecessor processes:
- Project Scope Statement
- Project Scope Management Plan
- generated by: Scope Planning
- Approved Change Requests
... introduced by external units:
- Organizational process assets
(2.3.2) Process Definition
Create WBS (Work Breakdown Structure) is the process which "[...] subdivides the major project deliverables and project work into smaller, more manageable components" (comp. PMBOK3, p. 103). The WBS itself is "a deliverable-oriented hierarchical decomposition of the work" which must be executed "[...] to accomplish the project objectives and create the required deliverables". And the decomposition is the explification of a part/whole-relation of task and subtasks in form of (mathematical) tree which ends in work packages as leaves of the tree (comp. PMBOK3, p. 112).
- Part of the Planning Process Group
- Child Process of Develop Project Management Plan
- Member of Knowledge Area Project Scope Management
The subject Scope operates on the base of other scope concerning concepts
(2.3.3) Tools and Techniques
PMBOK Mentioned Methods
- Work Breakdown Structure Templates might be inherited by other projects. Often they are representations of mathematical trees.
- Decomposition is the process of finding the parts and subparts of an entity; it's the recursively determination of tasks and their subtaks.
(comp. PMBOK3, pp. 113ff)
Open Source Tools
- myPmpsFactory offers a structured template for work break down structures. This template can be edited by Open Office 3 (Calc).
- Planner offers a project schedule file with integrated WBS structure representing the relational structure.
(2.3.4) Process Output
- Updates of the Project Scope Statement can be evoked by discovering necessary (but forgotten) task and subtasks.
- The Work Breakdown Structure is the tree of tasks and subtasks. And each leaf (= work package) - if not even each node (= more complex task) - of the tree is an identifier for a more elaborated task description which is noted in the WBS Dictionary.
- The WBS Dictionary contains detailed description for each work package (leaf) of the WBS.
- The Scope Baseline is the approved combination of Project scope statement,WBS and WBS Dictionary.
- Requested Changes may be generated by (iterative) refinings of the WBS
- Updates of the Project Scope Management Plan may be evoked by (iterative) refinings of the WBS
(comp. PMBOK3, pp. 117f)
(2.3.5) Output Using Successor Processes
Successors using the initially generated output as own input(1):
- Activity Definition
- Activity Sequencing
- Activity Duration Estimating
- Schedule Development
- Cost Estimating
- Cost Budgeting
- Quality Planning
- Communications Planning
- Risk Management Planning
- Risk Identification
- Qualitative Risk Analysis
- Quantitative Risk Analysis
- Plan Purchases and Acquisitions
- Integrated Change Control
- Scope Verification
- Scope Control