The following are examples of methods for testing the usability of computer interfaces (adapted from "Usability Assessment Methods beyond Testing")
| Method |
Stage in Process |
Users Needed |
Advantages |
Disadvantages |
| Traditional Testing |
Iterative design, formative evlauation, final testing |
3 + |
|
Time consuming and expensive |
| Heuristic evaluation |
Competitive analysis, final testing |
None |
Finds individual usability problems. Can address expert user issues. |
Does not involve real users, so does not find "suprises" relating to their needs. |
| Performance measures |
|
10 + |
Hard numbers. Results are easy to compare |
Does not find individual usability problems. |
| Thinking aloud |
Iterative design, formative evaluation |
3-5 |
Pinpoints user misconseptions. Inexpensive |
Unnatural for users. Hard for expert users to verbalize. |
| Observation |
Task analysis, follow up studies |
3 + |
Ecological validity; reveals users' real tasks. Suggests functions and features. |
Appointments hard to set up, No experimenter control |
| Surveys |
Task analysis, follow-up studies |
30 + |
Finds subjective user preferences. Easy to repeat |
Pilot work needed (to prevent misunderstandings). |
| Interviews |
Task analysis |
5 |
Flexible, in-depth attitude and experience probing. |
Time consuming. Hard to analyze and compare |
| Focus groups |
Task analysis, user involvement |
6-9 per group |
Spontaneous reactions and group dynamics. |
Hard to analyze. Low validity |
| Logging actual product use |
Final testing, follow-up studies |
20 + |
Finds highly used (or unused) features. Can run continuously. |
Analysis programs needed for huge mass of data. Violation of users' privacy |
| User feedback |
Follow-up studies |
unlimited |
Tracks changes in user requirements and views |
Organization needed to handle responses |
User Interface Design 
