5.3 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
5.3.2 Scope Definition - Tools and
220.127.116.11 Work breakdown structure
A WBS from a previous project can often be reused as a
template for new projects.
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
(1) Identify the major elements of the project eg project
management and deliverables.
- the phases of a project life cycle may be used as the
first level with project deliverables repeated at the
- the organizing principle within each branch may vary.
(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:
- are the lower level items both necessary and sufficient?
- is each item clearly and completely defined?
- can each item be appropriately schedule?
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5.3.3 Scope Definition - Outputs
18.104.22.168 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
- Code of accounts
- Each item in a WBS is generally assigned a unique
identifier. These are collectively called the code of
- 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
- 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
- Project breakdown structure (PBS)
- Same as WBS.
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