Avinash Kaushik (see his RSS on my homepage ), the author of “ Web Analytics - An Hour a Day” and “ Occams Razor” blog, wrote an excellent and comprehensive post on the methodology behind “ time on site” and “ time on page” metrics.

For all of you who always wonder how this is calculated and how come sometimes the numbers don’t seem too logic - Avinash exaplains the method from A to Z in a simple and logic way. Highly recommended!