Concerned about their privacy, consumers are increasingly deleting cookies from their computers, making Internet advertising measurement more difficult.
Now ubiquitous in online advertising, cookies are used to collect anonymous information about Web surfers, which is used for ad targeting and to measure its effects on e-commerce.
But cookies are now threatened by consumers fed up with computer intrusions, according to a recent Jupiter Research survey of 2,300 Web users. Over half of respondents said they cleared cookies from their hard drives at some point last year, and 38 percent said cookies are an invasion of privacy.
"This data does present a fairly frightening picture for online advertisers," said Eric Peterson, Jupiter analyst. He urges publishers and advertisers to consider non-cookie tracking, such as requiring site registration or using Macromedia Flash.
While many industry executives question the severity of the problem, most acknowledge that cookie sweeping is increasing."If its 40 percent, 20 or 10 [percent], it's still a number that affects everyone that sells online ads," said Dave Morgan, CEO of Tacoda Systems, a New York-based behavioral ad-targeting firm.
Third-party cookies from Web analytics companies and ad networks are at particular risk, Jupiter concluded, since 28 percent of users reject all third-party cookies. Popular spyware removal programs like Ad-Aware categorize third-party cookies with spyware programs tabbed for removal.
After seeing anti-spyware programs make as much as 15 percent of some clients' visitors anonymous, Coremetrics, a San Mateo, Calif.-based Web analytics provider, moved most of its clients from using third-party Coremetrics cookies to their own.