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Functional Decomposition – How Does It Apply to Agile? Why Is It Important?

What is Agile functional decomposition? (and why is it important?) Investopedia defines “functional decomposition” as follows:

“A method of business analysis that dissects a complex business process to show its individual elements. Functional decomposition facilitates the understanding and management of large and/or complex processes and can be used to help solve problems:

Functional Decomposition in Agile
  • Basically, functional decomposition takes something complicated and simplifies it
  • The individual elements of the process and their hierarchical relationship to each other are commonly displayed in a diagram called a functional decomposition diagram.”

How Is It Relevant to Agile?

Why is that relevant to Agile? A major goal of Agile is to maximize the business value that a project produces.

  • On small, simple projects, you might be able to easily discover what the business value is based on direct face-to-face discussion with the Product Owner and individual stakeholders
  • On large enterprise-level projects, that may not be so easy to do:
    • An example is that I was involved in a large project with about 500 user stories, and
    • We had to do some prioritization to move things out to a future release
    • Doing that on a project of that size without understanding the relationships among the stories can be very difficult if they’re not organized into some kind of functional hierarchy

Agile Functional Decomposition – Keeping Stories Well-Organized

Using functional decomposition to organize stories into epics and themes:

  • Makes it possible to keep all of the stories well-aligned with producing the higher-level business value that the project is intended to produce, and
  • It makes it a lot easier to effectively manage the Product Backlog

It also provides a capability for trace-ability

  • You can look at the top-level functionality and then look down into the functional decomposition to verify that the lower-level functionality is really complete and
  • That the lower-level functionality is sufficient to support the higher-level functionality.

Overall Summary

Functional decomposition has been around for years but many people don’t think it is relevant to Agile projects. It’s one of those traditional, plan-driven practices that people seem to assume is now obsolete and no longer relevant with Agile. I don’t believe that is the case.

  • You don’t have to completely throw away all the traditional plan-driven practices you may have learned in order to practice Agile and
  • Some of those practices become especially important as you begin to try to scale Agile to an enterprise level
  • Functional Decomposition is an example

Additional Resources

You will find much more detail on this in my Online Agile Project Management Training.

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