Purpose: Summative vs. Formative
You should establish usability criteria for your software, website or intranet or mobile application. In a call center, management wants to minimize average handle time (AHT). They might set a usability goal of keeping AHT below 30 seconds. In a medical clinic, physicians are concerned about errors. They might set a usability goal of keeping prescription errors below 0.5%.
These usability criteria, whether AHT or error rate, drive summative usability testing. This form of testing, typically completed at the end of software development but before deployment, is related to user acceptance testing. The software must pass the summative test before it can be deployed. If not, it needs changes based on feedback from formative testing.
Formative usability testing is the more common form of testing. It provides feedback on the software’s usability with the goal of improving the users’ experiences. Of all the different types of tests that can be conducted under the umbrella of formative usability testing, the most useful is user performance testing. Performance.
Can the users complete common tasks with your technology in typical environments? That is the essence of usability. With a user performance test, a user is given a task and asked to complete it while thinking aloud. As Yogi Berra once said, “You can observe a lot just by watching.” And by hearing the users’ thoughts you’ll come to understand how they see the world, what assumptions they make, and where the user interface confuses them.