thanks for the feedback on the tone. See constructive suggestion in my reply to awenger.
one comment on the survey vs. server log comparison: Survey also doesn't give you "why" on user behavior; it only give you what the user "thinks" the reason is. For certain occasions it provide false insights. Server logs are facts, you won't get why but you get concrete observations.
I agree that users don't give perfectly true answers, but discarding their answers as 100% useless or false is silly. You can corroborate survey results with server logs. You don't have to view them in isolation.
one comment on the survey vs. server log comparison: Survey also doesn't give you "why" on user behavior; it only give you what the user "thinks" the reason is. For certain occasions it provide false insights. Server logs are facts, you won't get why but you get concrete observations.