In my Google Anaylitics info, I see the duration of MANY visits to my site is 00:00:00. Why is that? My questions are: 1. Are these visitors human or robots? 2. Why and how come is this possible?
I too have the same problem...I think when people just come and go away without even taking a look, it happens.
I have some of that too, and it's because people will click on your site, and bounce right off, so they don't count any time.