Comment What about fingerprinting sites visited? (Score 1) 24
They only anonymise at the user level most likely. They know full well that site visits can be fingerprinted. Which groups of sites a user visits, especially together can be used to fingerprint many users, especially if there's more niche or specialised sites they visit (hobbies, interests etc). Match up a user's traffic fingerprint (from ad tracking on sites the ad company covers) against the 'anonymised' data and you now have full details of the individual's web browsing.
The only anonymised data I'd trist is where every site visit is assigned its own anonymised ID, breaking the link to the individual. That kinda defeats the purpose of the data though and most likely breaks the business case for such data ..... doh!