Study: Consumers Delete Cookies at Surprising Rate

Nearly 40 percent of Internet users delete cookies from their primary computers on at least a monthly basis, according to a study by JupiterResearch. The finding has big implications for advertising and marketing firms that depend on cookies for tracking and targeting.

Based on a survey of 2,337 U.S. respondents, the study finds that 17 percent of Internet users delete cookies on a weekly basis. Approximately 12 percent do so on a monthly basis, and 10 percent make it a daily habit.

“The key finding is that a lot of companies have placed a lot of reliance on cookies for audience measurement and the cookie is at risk as a mechanism for tracking people over time,” said Eric Petersen, the lead analyst on the report.

The trend challenges the notion that cookie-based methods produce accurate measurements for marketers. Measurements affected by the deletion of cookies include the number of returning visitors, unique visitors, multi-session campaign conversions, and lifetime value. Techniques like behavioral targeting and personalization are also highly dependant on cookies.

“Advertisers using lifetime value metrics need to reexamine how accurate that data is,” Petersen said. “The further away you get from the date the cookie was set, the less likely that the information is completely accurate.”

The primary reason consumers remove cookies is that they believe cookies threaten their privacy and security online. Consumers also lack an understanding of the time saving benefits cookies provide, Petersen said.

“For some reason, consumers have identified cookies incorrectly as spyware,” he added. “Consumers don’t understand what cookies do.”

The report found 28 percent of Internet users are selectively rejecting third party cookies, such as those placed by online ad networks. One company researchers interviewed said the number of visitors blocking third-party cookies has increased from less than three percent in January 2003 to 14 percent of visitors in January 2005. Peterson suggested site owners should turn instead to first-party cookies as a standard.

The report suggests that site owners also consider a registration/log-in model, which would allow publishers to re-set deleted cookies. For high-traffic sites where that would be impractical, Peterson suggests they consider using Macromedia Flash’s local shared objects, which are less likely to be spotted and removed by anti-spyware programs.

Companies with high-consideration products should pay particularly close attention to the conclusions of the report, said Bryan Eisenberg, co-founder of Future Now.

“From a Web analytics point of view, latency trafficking will be more difficult to do,” Eisenberg said. “For sites with products that have long sales cycles, it will be even more difficult to do, because you can’t track that traffic over time.”