Study: Google Tracking 88% Of Domains In Study
A new study published by graduate students at University of California, Berkeley showed that Google is the leading footprint on the top 100 sites in their study.
As you can see from the chart below, Google Analytics was found on 81% of the top 100 sites, while DoubleClick (owned by Google) was in second place, by being found on 70% of those sites. Microsoft came in third with Atlas showing up on 60% of those sites. Here is the chart:
When combining Google Analytics, DoubleClick, AdSense, Google Widgets, Google FriendConnect and others, Google has a 88% footprint on those sites:
The New York Times blog has additional commentary on the limited study.
Postscript: Google: Master Of Closing The Loop? by Danny from April 2007, Danny talked about this issue. Back then Google said they would not mix and match the data between products.