Usability quality is the ability of customers and end-users to complete tasks reasonably easily, simply and intuitively. Usability is recognised when users can use the software application without much thought resulting in the fast, efficient completion of tasks and avoiding feelings of being lost or confused. Usability is heavily associated with user interfaces and often driven by client-side code, although it also applies to application interfaces and documentation.
Usability quality is prioritised by stakeholders when user experience is important, particularly when user engagement is critical to organisation goals or increased costs due to technical support calls from users asking how to complete tasks.
Key supporting metrics may include:
- Time-to-figure-out how to complete a task
- Number or percentage of technical support tickets relating to poor usability
- Number of clicks/taps users have to make to complete a task
A software application that is used by IT systems administrators may need less attention paid to usability quality than a software application used by the general public. In the former’s case, they may prefer simple functional design or there’s less risk associated with poor usability so it needs less of a priority. Project stakeholders may prioritise usability quality much higher if there’s a risk that large numbers of people will be turned off from using the software. It’s also possible to have too much usability; helpful hints and guides meant for new users can quickly get in the way and slow more experienced users down. Testers evaluate usability quality by experiencing the software application and reporting anything which is difficult, confusing or a mystery to accomplish or gets in the way. A showstopper would be something that’s so difficult that a user wouldn’t be able to complete the task at all.
Threats to usability value may include:
- Clunky, unintuitive user interface design
- Hidden functionality that users can’t find how to interact with or simply don’t know about
- Mislabelled or misnamed features
- Too many hits or tips
- Unclear or missing help documentation or excessive tech support tickets reported
Famous usability bugs include:
- Due to a poor interface design, a CitiBank accidentally sent an entire loan due amount to creditors instead of just interest payments, which a judge ruled they weren’t entitled to claim back (Lee, 2021)
- Clippit, the infamous default Microsoft Office Assistant, is an example of too much usability. It tried to be too helpful in making it easy for only new users to complete tasks, but ultimately ended up hindering or distracting more experienced users from doing so (UneeQ, 2019).
Heuristics to test for usability quality may include:
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