A Comparison of Three Usability Evaluation Methods: Heuristic, Think-Aloud, and Performance Testing

A high-fidelity prototype of an extended voice mail application was created. We tested it using three distinct usability testing paradigms so that we could compare the quantity and quality of the information obtained using each. The three methods employed were (1) heuristic evaluation, in which usability experts critique the user interface, (2) think-aloud testing, in which naive subjects comment on the system as they use it, and (3) performance testing, in which task completion times and error rates are collected as naive subjects interact with the system. The three testing methodologies were roughly equivalent in their ability to detect a core set of usability problems on a per evaluator basis. However, the heuristic and think-aloud evaluations were generally more sensitive, uncovering a broader array of problems in the user interface. Implications of these findings are discussed in terms of the costs of doing the evaluations and in light of other work on this topic.