For quite a few years the University library where I work has used Google Analytics to track usage of our web pages. Recently I noticed it wasn't working. The code had some how disappeared from the page - possibly in a WordPress upgrade. It is working now.
Here is the oddity. Google Analytics never stopped reporting usage statistics. The University has its own tracking code so my assumption is they came from there. Is Google's system clever enough to know how to associate numbers for our account with the University one? Can the numbers I have be trusted?
After doing some further investigation, I can confirm our tracking code has not been properly implemented since October 2013. It was then when the University switched over WordPress which seems to have treated the code as Character Data. Then in mid-August 2015 the code vanished entirely. I now have it in an external file which seems to work fine. However while there has been a noticeable drop in web traffic from July 1, 2013 to the present, it does not entirely coincide with either the WordPress migration or the GA code's disappearance last summer.
I'm not entirely sure this answers the question, however. Google Analytics was giving a "tracking code mismatch" error until I re-inserted the code. However it still reported results. Exactly how accurate they were remains to be seen.