Recently during a client review we got into a discussion on how Google Analytics determines whether a visitor is new or returning and how long they are considered returning. I was pretty sure I knew the answer, but for the life of me could not remember the specifics. After the review, I had the itch to go on a researching expedition. I looked high and low for the answer, but even Google Analytics help was no help at all. The best I could find was this Google Analytics Help is usually pretty open about these things and I was a little shocked that I was unable to get the answer straight from Google. After that brick wall I kept searching and I eventually found out that that the first party cookie left by Google Analytics is not set to expire until 2038. What this means is that if the visitor has been to the site before they will be counted as a Returning Visitor, as long as they did not clear their cookies. If they did clear their cookies, Google Analytics will set/create a new cookie and count that visitor as a New Visitor. There is also one major distinction to keep in mind between Google Analytics and other Analytics Software. That distinction is that Google Analytics counts the number of visits generated by the visitors. Google Analytics does this by tallying up all the unique visitor IDs that were created during the period being reported against. For returning visitors it counts the number of unique visitor IDs that were created before the period being reported against. Google Analytics, for all intents and purposes, does not have an expiration date for Returning Visitors. Using the chart below as an example we see that there were 385 New Visitors for this time period and 52 Returning Visitors for a total of 437 Visitors. We can read that as during this reporting period, 52 visitors have been here sometime before, but the majority, 385 are New Visitors, and are here for the first time.
New Visitors Vs Returning Visitors