Comparative Evaluation of Usability Tests

Four commercial usability labs have carried out a professional usability test of the same calendar program. This paper discusses similarities and differences in process, reporting and results. There are two basic forms of comparative usability testing: 1. One professional lab tests several applications within the same subject area 2. Several professional labs test the same application. Form (1) is rather well-known. However, there are few (if any) documented comparisons of professional usability tests