Researchers from U Minnesota, UC Irvine and CMU took a look into “behavioural based advertisement”, a segment that requires heavy tracking of users across websites through cookies. A report of their findings is here: Online Tracking and Publishers’ Revenues: An Empirical Analysis. Money quote:
They found that despite the 40% “ad-tech” premium charged by behavioral ad companies, the ads only added about 4% the media companies that published them, meaning that behavioral advertising is a losing proposition.
Source: Boing Boing