Insert Cookie Joke Here : The Commerce360 Blog

Moving quickly beyond the fact that it is a a major panel-based audience measurement company releasing a study that says (surprise) cookies aren't accurate, the study is most likely completely accurate and there are several interesting facts contained therein:

31 percent of U.S. Internet users cleared their first-party cookies during the month.
Within this user segment, the study found an average of 4.7 different cookies for the site.
Among the 7-percent of computers with at least 4 cookie resets, comScore counted an average of 12.5 distinct first-party cookies per computer, accounting for 35 percent of all cookies observed in the analysis.
Web site server logs that count unique cookies to measure unique visitors are likely to be exaggerating the size of the site’s audience by a factor as high as 2.5, or an overstatement of 150 percent.
comScore’s analysis of third-party cookies revealed an average of 2.6 distinct cookies per computer in December, indicating a similar rate of overstatement as the first-party cookies.

Further proof that web analytics are true but not accurate (a most excellent quote I heard from Jim Sterne).

Definitely a problem if you're a brand marketer paying for coverage across unique humans. Much less of an issue if you're an online retailer trying to understand visitor behavior. Sure the numbers won't be right (did you really think they were?) but the trends should be true and accurate. Don't forget it's not just uniques that is affected - things like ave-number-visits-before-purchase and similarly 'cookie-based' cumulative measurements are also equally impacted.

Two thoughts:

What if web analytics software provided an option to compensate for the likely overcounting of uniques due to cookie deletion. A simple place we could tell it to decrease the unique visitor count by 33% (or whatever) because that's what we believe our overstatement rate to be. Wouldn't it be nice to just quickly see reports with this clean-up IF we believed that made them more accurate?

Any chance we could get all those cookie deletion utilities to empty them out and then write a new cookie telling the rest of us the date of the last flush?

Related Discussion: AVC AttentionMax

Comments

Ah! Another Spring Cookie Deletion news. Don't we love'em! I wonder what the case would be if the antispyware applications just stopped identifying 1st-party cookies as potential threat. But I hear they don't. Which would mean that 31% of users actually delete them manually? Hmmm.

I like your idea of having the possibility to tell the app by how much it should bring the visitor number down, although coming up with a realistic number wouldn't be easy.

Anyway, there are a lot of interesting topics in web analytics these days, and exciting stuff to address (data system integration, etc.), but, darn, we ARE going to have to solve the visitor counting issue one of those days!

Posted by: Jacques Warren | April 17, 2007 7:13 AM