Contextual Interviews

I think contextual interviews over the phone would be incredibly difficult to manage. Even with incentives, in the fast-paced and gimmicky world that we live in, I am not sure anyone would stay on the phone for 30 minutes to go through a series of questions for a website. The idea of contextual interviews in general is very helpful to the overall process, however, I can't imagine having much success over the phone. And the cost very much surprised me for formal usability tests: $10,000-$20,000 for one day with a consultant, a facility and ten participants.