• by Tom Hespos , April 19, 2005

I won't take offense if you call me "Chicken Little."

Young-Bean Song, director of analytics at Atlas Solutions, released a white paper to me last week concerning cookie lifespan, a subject near and dear to my heart. In it, he claims "[c]ookie-based reporting and analysis continue to provide reliable metrics to measure and optimize online campaigns."

Since recent reports from several research companies have pegged percentages of online users who delete cookies at least monthly at anywhere between 39 and 55 percent, there has been a great deal of concern regarding how cookie deletion affects ad campaign reporting. And with good reason. Cookie deletion can adversely affect conversion tracking, reach, and frequency statistics, frequency capping, and a whole lot more.

However, Song and the folks at Atlas found there is a significant difference between self-reported behavior and what one might expect to find with regard to cookie "lifespan." In the white paper, Song said survey respondents who claimed to delete cookies weekly had an average cookie lifespan of 45 days, and not the seven days one would expect. "[W]hat people say and what they do is often not the same," he said in the white paper.

This is music to my ears. However, I don't think it would be wise to assume the problem doesn't exist or that it will go away on its own. Neither does Song. "Our intent here is not to trivialize the results of the survey studies," he said in the release. "However, we believe that a more complete study which incorporates actual user behavior is a much better way to formulate a true picture of what's going on." He indicated that The Atlas Institute has launched several additional studies, including one with the Advertising Research Foundation (ARF).

The fact remains, however, that several popular anti-spyware software packages available for download and/or purchase online have been identifying ad server cookies as potential threats as a default, and this could be prompting widespread cookie deletion as more people download and run the software. As I mentioned in a previous column, two such popular packages - Spybot: Search & Destroy and Ad-Aware - have been downloaded hundreds of millions of times from Download.com. While the average cookie lifespan may currently be long enough to convince us that the sky isn't crashing down on us, cookie deletion is almost certainly becoming more widespread. It's something we need to watch carefully.

Regarding reach and frequency reporting, Song said in the Atlas release that Atlas Reach and Frequency reports routinely make use of a "statistical filtering methodology that corrects for this bias." Basing analysis on "massive samples of stable cookies" helps Atlas "minimize the impact of cookie deletion and provide reliable reach and frequency reporting at very granular levels," according to the release.

Personally, I'm watching these issues like a hawk. Atlas has indicated that they will provide me with some additional information for a potential follow-up to this release. I do agree that actual online behavior should serve as the basis for future analysis of the problem. After all, folks might claim to clear their cookies regularly, but they also probably claim to floss regularly and to never use swear words. Indeed, what people do often differs significantly from what they say they do.