Time on site
Clicky's time on site values are more accurate than most other services because our tracking code will continue to ping our servers while a visitor sits on a single page. This gives us a much more accurate picture of how the visitor was actually on your site.
Services that do not ping, which is most of them, calculate time on site as the difference between the time of the first page view and the last. With Clicky, for a visitor's final page view, we will ping our servers while that visitor engages with the final page. So our time on site is the difference between the time of the first page view and the time of the last ping of the last page view.
Because pinging can take up a lot of extra bandwidth, a paid account is required for this to work. Otherwise, our time on site values will only be based on the difference in time between the first and last page view of a visit.