Types of Usability Tests

The great thing about usability testing is that it is used in several places within the UX lifecycle.

In the Discover phase, you might test people on the current system to learn what currently works and doesn’t. This would be a summative test of an existing system.

Jeff Sauro of Measuring U explains the difference between formative and summative tests:

  • “Formative” refers to usability studies in which the primary activity is the detection and, through iterative design, elimination (or reducing the impact) of usability problems. 
  • Summative refers to usability studies in which the primary activity is collecting objective and subjective measurements related to the accomplishment of a set of tasks.


When would you use either of these?

  • Formative tests can take place anywhere in the design cycle, but most likely occur in the Design phase. These are the tests we do in the ‘Test’ portion of Ideate, Prototype, and Test.
  • Summative tests are most likely to take place post-release and prior to design.

Besides formative and summative, another distinction is based on whether or not you are measuring performance.

In many of our tests we are gathering users’ opinions about our design, and measure only whether or not a user can complete a task. We might ask the participant to ‘think out loud’ and give her impressions of each screen and the overall flow. These are qualitative tests.

If we are measuring performance, we are most likely timing the completion of each task, resulting in quantitative data. Other common measurements are task completion rate, number of errors, and the user’s self-reported satisfaction.

When we measure performance, we are typically either:

  • Comparing performance against a benchmark, or
  • Comparing performance against another interface


In this short article, Jeff Sauro discusses the 5 types of usability tests