Usability testing is an effective way to verify an existing design or system. It is a structured observation of users in a laboratory setting. Users are observed performing important tasks with a working system or prototype. They are asked to “think aloud” while completing the tasks. This includes describing what they are trying to do, the hypotheses they are forming, their expected results of an action, etc. The evaluator observes the user’s performance noting problems, comments, circuitous paths, etc. Usability tests are useful for collecting quantitative data regarding time per task and number of errors. (Rubin, 1994)
The evaluator always explains to users that only the software is being tested, not the user themselves. Debriefing is usually included to get gather additional information about the user’s experience. A usability test is typically videotaped so the evaluator may perform more detailed observations and analysis after the test.