Looks like Google isn’t the only guilty party when it comes to advertising cookies.
Andrew Carr-Smith sent me this link from Stanford University’s Center for Internet and Society (CIS), which has been tracking how the advertising networks track us.
This is slightly different from my earlier situation, which did not involve the ‘Do Not Track’ programme that one can ﬁnd in Firefox 5. Mine was strictly about the opting out of behavioural targeting using Google’s own opt-out system, and that of the Network Advertising Initiative. Still, the implications for privacy remain interesting.
You might think you’ve asked them not to track you, but they do:
Half of the NAI members we tested did not remove their tracking cookies after opting out.
NAI member companies pledge only to allow opting out of behavioral ad targeting, not tracking. Of the 64 companies we studied, 32 left tracking cookies in place after opting out.
At least eight NAI members promise to stop tracking after opting out, but nonetheless leave tracking cookies in place.
According to the Stanford study, only two ad networks ‘are taking overt steps to respect Do Not Track’: Media6Degrees and BlueKai. Interestingly, Google was one of networks that ‘go beyond their privacy policies and remove their tracking cookies.’
I have to wonder whether it was because it got busted with its lies about opting out.
The ad networks have provided responses at the bottom of the page, mostly positive.