What is usability testing

In A Practical Guide to Usability Testing, (1994) Joseph Dumas and Janice Redish provide a constructive definition of usability. They wrote, “Usability means that the people who use the product can do so quickly and easily to accomplish their own tasks.” (p. 4) Their definition of usability can be simplified to four basic components:

1. When we talk about “usability,” we are really talking about the user of the product
2. We must start with the assumption that real people use real products to be productive
3. These real people are busy people, they can’t afford to waste time re-learning the product every time they use it
4. These real people are the only ones who can definitely tell you if the system is easy to use or hard to use

In other, more academic definitions of usability, you might find terms like Discoverability (how easily users can uncover the features of the system) or Learnability (how easily users can learn to use these features) and Memorability (how well these users will remember how to do it the next time they use the system and Error Rate (how easily users can create mistakes or errors when trying to use a system they are unfamiliar with).

No matter how you define usability, it’s important to recognize that usability is not the same as unit testing or acceptance testing. Usability is a different concept that captures how typical users of the system with average knowledge about the process should be able to use the system to perform tasks. In other words, usability testing is about real people using the system to do real work in a reasonable amount of time.

As such, the real purpose of a usability test is to uncover issues that prevent real people from doing real work.

Usability testing is part of development

Whatever method you use to examine the usability of a product, the value of the usability test is in performing the evaluation during development of the system. Waiting until you have a completed version and then doing usability testing is much too late in the process. At that point, making any changes to the design will become much more difficult, and may require rewriting large parts of the system to address any usability issues.

To be successful, usability tests must be part of the design and development process, and addressed as part of a software development process.