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5.3 Scope Definition


Scope definition involves sub-dividing the major project deliverables (as identified in the scope statement) into smaller, more manageable components in order to:

  • improve the accuracy of cost, time and resource estimates

  • define a baseline for performance measurement and control

  • facilitate clear responsibility assignments.

5.3.1 Inputs

  1. Scope statement
  2. Constraints
  3. Assumptions
  4. Other planning outputs
  5. Historical information

5.3.2 Tools & Techniques

  1. Work breakdown structure templates
  2. Decomposition

5.3.3 Outputs

  1. Work breakdown structure







5.3.2 Scope Definition - Tools and Techniques Work breakdown structure templates

A WBS from a previous project can often be reused as a template for new projects. Decomposition

This involves subdividing the major project deliverables into smaller, more manageable components until the deliverables are defined in sufficient detail to support future project activities (planning, executing, controlling and closing). The steps in decomposition are:

(1) Identify the major elements of the project eg project management and deliverables.

(2) Decide if adequate cost and duration estimates can be developed at this level of detail for each element. More decomposition may be required.

(3) Identify constituent elements of each deliverable. These should be described in terms of tangible, verifiable results in order to facilitate performance measurement.

(4) Verify correctness of each decomposition:

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5.3.3 Scope Definition - Outputs Work breakdown structure

A work breakdown structure is a deliverable-oriented grouping of project elements that organises and defines the total scope of the project. As with the scope statement, the WBS is often used to develop or confirm a common understanding of project scope.

Code of accounts
Each item in a WBS is generally assigned a unique identifier. These are collectively called the code of accounts.
Work package
The items at the lowest level of the WBS are referred to as work packages. These work packages may then be decomposed as part of Activity Definition.
WBS dictionary
This is used to collect work element descriptions and will include work package descriptions as well as other planning information such as schedule dates, cost budgets and staff assignments.
Contractual WBS (CWBS)
This is used to define the level of reporting the supplier will provide the buyer. The CWBS generally includes less detail than the WBS used by the seller to manage the seller's work.
Organizational breakdown structure (OBS)
This is used to show which work elements have been assigned to which organizational units.
Resource breakdown structure (RBS)
Used when work elements are assigned to individuals.
Bill of materials (BOM)
Presents a hierarchical view of the physical assemblies and sub-assemblies and components needed to fabricate a manufactured product.
Project breakdown structure (PBS)
Same as WBS.


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