Cookie Inflation


Has your website been doing gangbusters recently? Think again. As Comscore explains, you may be just be welcoming back a single visitor with OCD.

Techcrunch is covering a mini-soap opera today starring Comscore’s web analytics business. Linda Abraham, Comscore’s CMO jumped in with some thoughts:

1) First of all, we measure Unique People rather than Unique Cookies which web analytics systems erroneously can unique visitors. I would challenge you to find any kind of server side measurement system that measures people, not machines or cookies. To show you how absurd server side numbers are, AOL Inc. had about 259 MM Unique cookies which gives it over 125% reach compared to a true reach of 54%. The inflation is driven by cookie deletion, multiple browsers, multiple machines for the same users, multiple devices etc… Large companies do not complain about their numbers because they know their server side numbers are flawed as obviously evident by the AOL metrics, not because “comScore fixes your number”. This dynamic is less obvious with smaller sites—they don’t realize how inflated their numbers are until their reach starts exceeding 100%.

(emphasis mine)

You’re probably asking yourself how bloated are those “unique visitor” numbers in your analytics software? Unfortunately, there is no universal flat rate that will reduce your numbers to provide an accurate reading. In general, if returning visitors make up a large portion of your traffic, your inflation rate will be running higher than would otherwise be the case.
In the longer term, these concerns will diminish. As the personalized/mobile computing trend accelerates, people will be online with the devices in their own pockets and time on shared systems will diminish in proportion to their overall online life. When not on the go, people’s mobile devices will sync with their more stationary brethren.

In the meantime, how would you quantify the concerns laid out by Comscore’s Linda Abraham? What formula or method are you already using to get an accurate reading?

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