Google Analytics: Updated visit definition is missing visits
Google updated their definition of a visit in the middle of august. I’ve written an explanation in a separate blog post. In general the change is good as it should make the data in Google Analytics easier for the layman to interpret.
What isn’t so good is that Google Analytics isn’t behaving in the way Google describes. It’s not only missing visitors in some situations, but it is also missing some traffic sources – the attribution is totally incorrect for some visits.
Test details
My test was as follows:
Using my Android tablet, I visited my blog a series of 4 times. I used my tablet so that it would be easy to extract my test visits (with little chance of anyone else visiting the same pages from the same sources on that day).
Visit 1
Via a link on one of my old sites, www.ccl4.org The browser newly opened Not visited beantin.se in the past 30 minutes.
Visit 2
Via Google's search results searching for beantin fishbang A few minutes after visit 1.
Visit 3
via Google again, this time searching for beantin seo The browser newly opened Over 60 minutes since visit 2.
Visit 4
Via a link on another one of my old sites, 503.org.uk Just a few minutes after visit 3.
According to Google’s new visit definition, this should have been 4 visits, with 4 different traffic sources.
What the data contained
According to my Google Analytics data, I had made 3 visits. Visit 4 is missing. Instead, you can see that the beantin seo search has had 2 page views attributed to it – which you can see from my test actions simply isn’t true.
Showing all 4 visits happened
As a way of confirming that visit 4 really did happen and data was received by Google Analytics, showing the referral from 503.org.uk, I made use of my per visit referrer script.
On beantin.se this script saves the referrer for each visit as a custom variable. The script is run on each page view, and the referrer is saved to the custom variable at the visit level.
This means visit 4 will have over-written the referrer for visit 3 – as Google hasn’t trigger a new visit for visit 4, but there is a page view, so my script grabs the referrer…
As you can see from the screenshot, 503.org.uk is there – meaning a visit did come from that site, and there are two page views attributed to it (the page views from visits 3 and 4).
Bug or feature?
I’ve repeated this test on my laptop and examined the cookies after each visit, and Google Analytics is failing to update the traffic source (in __utmz) and subsequently failing to trigger a “new visit” according to their new definition.
A bug or a feature? I say bug… what do you think?
Update 20110915
When researching this blog post, I focused my attention on the __utmz cookie. I’ve just taken a closer look at how both __utma and __utmz are behaving in the above scenario.
Google Analytics is failing to update not only the traffic source, but also the visit count and the various timestamps stored in __utma detailing when you last and current visits took place.
This means that even more reports in Google Analytics could be affected (depending on your visitor patterns)