I'm pushing usability testing within my workplace by performing some Steve Krug style usability tests, which have gone down so well that the product owner now wants me to add some marketing questions.
It's her budget, and the questions are perfectly sensible, but I need to explain what usability tests are good at and not so good at. It seems to me that by concentrating on observed behaviour we avoid what I think of as "Please the listener" or "Please the interviewer" bias, whereas straightforward marketing questions could fall into this trap.
In order for me to make this point as helpfully and authoritatively as possible, can someone tell me what this bias is called, and if there is any research to demonstrate its magnitude?