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Techniques
Functional Decomposition
10.22 Functional Decomposition
10.22.1 Purpose
10.22.2 Description
Functional decomposition helps manage complexity and reduce uncertainty by
breaking down processes, systems, functional areas, or deliverables into their
simpler constituent parts and allowing each part to be analyzed independently.
Process 1.1
Functional decomposition approaches the analysis of complex systems and
concepts by considering them as a set of collaborating or related functions,
effects, and components. This isolation helps reduce the complexity of the
analysis. Breaking down larger components into sub-components allows scaling,
tracking, and measuring work effort for each of them. It also facilitates evaluation
of the success of each sub-component as it relates to other larger or smaller
components.
The depth of decomposition may vary depending on the nature of components
and objectives. Functional decomposition assumes that sub-components can and
do completely describe their parent components. Any sub-component can have
only one parent component when developing the functional hierarchy.
The diagram below provides an example of how a function can be broken down
to manageable, measurable sub-components.
Figure 10.22.1: Functional Decomposition Diagram
Subfunction
1
Process 1.2
Process 1.3
Function
Subfunction
2
Process 2.1 Process 2.2 Process 2.3 Process 2.4
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Activity 1.1.1
Activity 1.2.1
Process 2.1.1
Activity 1.1.2 Activity 1.2.2
Process 2.2.2
Activity 1.1.3
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