Agile design and usability: Will a prototype do?

The Agile Manifesto includes twelve principles. These two are related:

Deliver working software frequently [in short sprints that last] from a couple of weeks to a couple of months, with a preference to the shorter timescale.

Working software is the primary measure of progress.

From discussions with other practitioners, I know that software teams can get dogmatic about the above principles, and often work in sprints of one, two, or three weeks in duration to ensure they deliver frequently. Since the classic software-development problem has been delivering the wrong features too late, I understand the desire to deliver working software frequently, with more frequent opportunity for customer feedback.

When the “deliver frequently” principle becomes a fixation, though, other things can get bruised in the rush to produce working software. Consider design and usability research. Sometimes a system’s features are complex and interrelated. Sometimes an elegant and simple solution is elusive. (Technical limitations can contribute to this.) Sometimes a weak design needs testing to make sure it is usable. To ensure design and usability work gets the time it needs, this work is often moved to preceding and successive sprints. This sets the designer and usability analyst apart from the rest of the team.

Here are my ideas to help design and usability work integrate better into short sprints:

  • Ensure a designer understands the entire set of features before the first sprint. Ask for a broad-strokes design for the whole, and share it, so the team has a vision for the user experience. Before a sprint completes, compare the working software to the user-experience vision.
  • Agile tries to keep the deliverable as simple as possible, but simple features from different sprints may not combine into a good user experience. This is a defect, to be fixed like any other bug, before the sprint completes.
  • Ensure that usability and design bugs are resolved, by testing with users to validate the changes.
  • When you need work done that substantially shapes the user experience but that is not related to a specific feature, regard this user-experience work just as you regard database, architectural, or other foundational work. Foundation work is easier for the team to prioritise when planning a sprint.

The above suggestions work within the “deliver working software frequently” principle. I have another suggestion that pushes at Agile’s envelope.

It works!

I think the words “working software” are too restrictive. In my opinion, there are other deliverables that are equal to working software, especially for teams that use very short sprints. A deliverable such as a paper prototype or a low-fidelity interactive prototype is equal to a piece of code, and allows team members—all team members on an Agile team—to focus on design, prototyping, and validation together instead of making a designer or usability work one sprint ahead or one sprint behind the rest of the team.