443f18ee_ndard_Metrics___Analytics_Talk__WAA_Definition
[Compliant] Yes [Term] Visit Duration [GA Definition] Same as WAA Note: Google Analytics uses a different name for this metric. It is called ‘Average Time on Site’. The average time on site is calculated by dividing the total time spent on the site by the total number of Visits. [WAA Definition] 
The length of time in a session. Calculation is typically the timestamp of the last activity in the session minus the timestamp of the first activity of the session.
Google Analytics Compliance with WAA Standard Metrics - Analytics Talk
WAA Definition