Which term is not applicable when assessing requirement changes?

Functional decomposition refers to breaking down complex systems or processes into simpler, more manageable components to understand the functionality better. It is predominantly used during the requirements gathering phase to ensure clarity and completeness of requirements, rather than in the assessment of changes to existing requirements.

On the other hand, impact analysis evaluates the consequences of proposed changes, providing insights into how modifications will affect other components of the project. Estimation is involved in determining the effort, time, and cost required to implement changes. Traceability ensures that requirements can be tracked throughout the project lifecycle, illustrating how changes might affect existing requirements and their relationships.

Therefore, while impact analysis, estimation, and traceability are crucial for assessing requirement changes, functional decomposition does not apply in this context, as it does not directly address the assessment of changes.