| Method Name |
Lifecycle Stage | Users Needed |
Main Advantage | Main Disadvantage |
|---|---|---|---|---|
| Heuristic evaluation | Early design, "inner cycle" of iterative design | None | Finds individual usability problems. Can address expert user issues. | Does not involve real users, so does not find "suprises" relating to theier needs. |
| Performance measures | Competitive analysis, final testing | At least 10 | Hard numbers. Results easy to compare. | Does not find individual usability problems. |
| Thinking aloud | Iterative design, formative evaluation | 3-5 | Pinpoints user misconceptions. Cheap test. | Unnatural for users. Hard for expert users to verbalize. |
| Observation | Task analysis, follow-up studies | 3 or more | Ecological validity; reveals userīs real tasks. Suggests functions and features. | Appointments hard to set up. No experimenter control. |
| Questionnaires | Task analysis, follow-up studies | At least 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 use | Final testing, follow-up studies | At least 20 | Finds highly used (or unused) features. Can run continuously. | Analysis programs needed for huge mass of data. Violation of usersīprivacy. |
| User feedback | Follow-up studies | Hundreds | Tracks changes in user requirements and views. | Special organisation needed to handle replies. |