The growth of this type of ad targeting also raises a host of privacy concerns, but setting those aside for a second, do these ads even work? Do they perform better than regular ads? If they did, you’d expect advertisers to pay more for them and for Website publishers to be flocking to them.
At least for Google, the answer seems to be “No.” According to estimates by Jim Brock, founder of PrivacyChoice, chairman of Attributor, and a former senior VP at Yahoo, only about 25 percent of AdSense sites are serving targeted ads, which Google calls “interest-based advertising.”
