A few days ago Google made a few changes in the way sessions are calculated in Google Analytics.

Currently, Google Analytics ends a session when:

  • More than 30 minutes have elapsed between pageviews for a single visitor.
  • At the end of a day.
  • When a visitor closes their browser.
If any of these events occur, then the next pageview from the visitor will start a new session.
In the new model, Google Analytics will end a session when:
  • More than 30 minutes have elapsed between pageviews for a single visitor.
  • At the end of a day.
  • When any traffic source value for the user changes. Traffic source information includes: utm_source, utm_medium, utm_term, utm_content, utm_id, utm_campaign, and gclid.

If any of these events occurs, the next page the visitor views will count as a new session.

How will this affect our Google Analytics data?

This change will apply only to new visitors. Historical data remains unchanged.

Google aims to align the definition of session with a common visit, so that if a visitor leaves our site and comes back via a different source of traffic (search engines, direct traffic ,referring sites, etc), that user will show up in Analytics as a new visitor.

Those who are interested in knowing how Google’s algorithm update “Panda” affected their traffic, will find  a more reliable comparison for “unique users” in Google Analyics.