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Decomposition

Decomposition is a technique used to divide and subdivide the project scope and deliverables into smaller, more manageable parts until the work is defined at the work package level.

Explanation

Decomposition is the primary technique used in the Create WBS process and is also used in the Define Activities process. In scope management, decomposition breaks the project scope statement and deliverables into progressively smaller, more manageable components, ultimately producing work packages at the lowest level of the WBS.

The process typically follows these steps: identify and analyze the deliverables, structure and organize the WBS (by phase, deliverable, or subproject), decompose upper WBS levels into lower-level components, develop and assign identification codes to WBS components, and verify that the degree of decomposition is adequate for management and control purposes.

A key principle governing decomposition is the 100% rule: the total scope of each parent element must be fully accounted for in its child elements, with nothing missing and nothing duplicated. Over-decomposition should be avoided, as it can lead to excessive management overhead without proportional benefit. Under-decomposition can leave work packages too large to estimate and control reliably.

Key Points

  • Primary technique in Create WBS and Define Activities
  • Breaks scope into progressively smaller, manageable components
  • Must follow the 100% rule at every level
  • Avoid both over-decomposition and under-decomposition

Exam Tip

Decomposition is used in two processes: Create WBS (to break deliverables into work packages) and Define Activities (to break work packages into activities). Know both applications.

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