An Eye on User Data: An Interview with Jared Spool, Founding Principal of User Interface Engineering
http://webword.com/interviews/spool.html

Spool, Jared M.
WebWord
1999

Abstract:

Our most striking finding is how bad web sites are in general. We have yet to find a site where, if you choose questions at random based on information the developers have placed on the site, users can find the answers more than 50% of the time. (The best we've found is 42% of the time.)