What's the explanation for records of users in Google Analytics whom are listed for spending 0:00 minutes on the site, even though they're logged as a unique visit? Is this an error with Analytics? I get an awful lot of these every day, for a year or so.
Somebody has to click on a second page on the site to be able to start determining time. If they view a page and then either hit back or enter a different URL without clicking on anything, there is no way for the analytics to know how long they were around.