Contrary to claims that usability professionals operate scientifically to identify problems in an interface Who claims that? I think usability testing is one

Contrary to claims that usability professionals operate scientifically to identify problems in an interface Who claims that? I think usability testing is one of the most subjective practices out there. Oh right, the author of this article (and the authors of the previous studies too!) is muddying the waters of what is "usability testing" and "usability evaluation". Usability testing normally implies testing with a user. This sounds like all these studies were heuristic evaluations. If everyone had the same set of heuristics/best practices, then yes, it would be surprising for there to be a difference.