Applicable stages: design, code, test, and deployment.
Personnel needed for the evaluation: Usability experts: 1 Software developers: 0 Users: 4	Usability issues covered: Effectiveness: Yes Efficiency: No Satisfaction: Yes
Can be conducted remotely: No	Can obtain quantitative data: No

 Overview

This technique can be used for usability test, where the participants are allowed to ask any system-related questions of an expert coach who will answer to the best of his or her ability. Usually the tester serves as the coach. One variant of the method involves a separate expert user serving as the coach, while the tester observes both the interaction between the participant and the computer, and the interaction between the participant and the coach.

The purpose of this technique is to discover the information needs of users in order to provide better training and documentation, as well as possibly redesign the interface to avoid the need for the questions. When an expert user is used as the coach, the expert user's mental model of the system can also be analyzed by the tester.

The tester can also control the answers to certain predetermined information. In an extensive series of experiments, one could vary the coach's answers in order to learn what types of answers helped users the most. But this requires skilled and careful coaches since they need to compose answers on the fly to unpredictable user questions.

References

1. J. Nielsen "Usability Engineering", pp.199-200, Academic Press, 1993.