[dredmorbius]

Y'know, something more than a naked link is going to be just a smidge more useful and informative:

AreWePrivateYet recreates Stanford University's Tracking the Trackers: Self-Help Tools study on a continuous basis in a reproducible way. The above chart compares the level of protection provided by the different privacy extensions across various metrics.

[aj]

It is also worth mentioning that http://www.areweprivateyet.com/ is created and maintained by Evidon, the makers of Ghostery (and unfortunately, they have no placed any obvious disclaimer except the footer mention and the top right ghostery logo which is not entirely sufficient imo