Accurate Website Visitor Measurement Crippled by Cookie Blocking and Deletion, JupiterResearch Finds

According to JupiterResearch's recently released report, "Measuring Unique Visitors: Addressing the Dramatic Decline in the Accuracy of Cookie-Based Measurement," in 2004 58% of online users have deleted "cookies", which are small files often deposited on their computers by Web sites they visit. Tracking cookies is a principal means Web site operators use to track visitors, personalize their sites, and account for the effectiveness of marketing campaigns and Web site enhancements. If users delete cookies, accurate long-term measurement of consumer behavior on the site is severely compromised. If users block cookies, accurate short-term measurement is compromised, relegating increasing numbers of Web visitors to "anonymous" status.

The report found that as many as 39% of online users may be deleting cookies from their primary computer monthly, undermining the usefulness of cookie-based measurement and leaving many site operators flying blind. "Given the number of sites and applications that depend heavily on cookies for accuracy and functionality, the lack of this data represents significant risk for many companies," says Eric T. Peterson, Analyst at JupiterResearch. "Because personalization, tracking and targeting solutions require cookies to identify Web visitors over multiple sessions, the accuracy of these solutions has become highly suspect, especially over longer periods of time," added Peterson.

Privacy and security concerns on the part of online users are responsible for the cookie-deletion behavior that JupiterResearch has found. According to a recent consumer survey cited in the report, 52% of online users indicate a strong interest in stories and articles about Internet security and privacy, while 38% of online users believe that cookies are an invasion of their security and privacy online and 44% of online users believe that deleting or blocking cookies will protect them.

The JupiterResearch report provides advice to site operators for how to cope with the decline in accuracy of visitor measurement and predicts that Web analytics vendors will adapt their tools in the face of a consumer landscape that makes established measurement practices unreliable.