Google announced that beginning August 11 there will be a change in how Google Analytics calculates a session. For clarification, a session is provided in Google Analytics visits. Visits, by definition in Google Analytics: A count of sessions that have been active on your site for the selected date range.
Prior to this change visitor sessions were considered ended by Google Analytics when one of the three things happened:
- 30 minutes of inactivity between pageviews for a visitor
- End of a day (midnight arrives for the time zone settings in the profile for that report)
- Close of the browser
If any of these three things happened, the next pageview of the visitor was considered the start of a new session. The new calculation will still end the session on the first two bullets above but will also end when the visitors traffic source changes. Traffic source information for Google Analytics is based on their cookie values: utm_source, utm_medium, utm_term, utm_content, utm_id,utm_campaign, and gclid (auto tagging from AdWords). Closing the browser does not automatically end the session. And as with the old calculation, if any of these items occur, the next pageview will start a new session for that visitor.
How Does This Affect My Data?
Data prior to August 11 will not be changed, only data after this data will change. Google indicates that this change brings the definition of a session more in line with the definition of a visit. According to Google, with new sessions being started for new traffic source information essentially brings a more accurate attribution. While this might be true for visit information, conversions or ecommerce transactions were already being attributed to the new traffic source information. Which is why we have implemented a first click/last click analysis and utilize the multi-channel funnels aggressively.
With sessions not being automatically ended with the close of the browser for a short time, sessions can now model the user’s engagement with the website. With this change, the number of visits can increase, but Google indicates most users should see a less than 1% change. Obviously the more unique your website and tracking, the more this can play into the data change.