At the Interactive Advertising Bureau's Audience Measurement Leadership Forum this past Monday, its Audience Measurement Reach Guidelines document was released for public comment. This document, over 18 months in the making and a joint initiative between the IAB and the Media Research Council, goes a long way in helping sort out the differences in methods different sources use to count and report on Internet audiences.
Perhaps most helpful, the document makes the point that the term "Unique" is itself misleading. Unique Visitors or Users (i.e. People), Unique Browsers, Unique Devices, and Unique Cookies are all very different things, and the user of audience measurement data must understand these differences in order to correctly interpret the data, notes the document.
One of the foundational principles upon which the guidelines are based is that "client-Initiated Counting is crucial... [and] that counting should occur on the client side, not the server side, and that counting should occur as close as possible to the final delivery of an ad to the client."
I think this finding, coming from the IAB, will have a huge impact on the dialogue taking place in the industry around audiences.
Publisher executives are accustomed to seeing regular reports from their Web analytics group that track KPIs, logically including one called "Uniques." When people-centric data provided by market research suppliers deviate from internal site-centric Unique counts, much hand wringing (and worse) ensues. The reality is that site-server data do not measure people, but instead count unique cookies, which, because of cookie deletion and multiple browser usage, can greatly overstate the true number of different people visiting. I am hopeful that the IAB document will be a great tool for educating all parties in the industry about the differences between site-centric (aka Web analytic data) and people-centric, audience measurement data.
The document also explains appropriate filtrations that should be applied to site-centric counts in order to reasonably compare them to people-centric counts. One such filtration is to exclude international traffic. On more than one occasion, I've worked with a publisher who was convinced that comScore Media Metrix data were undercounting their audience because they compared our U.S. Media Metrix data to their internal Unique counts. After some investigation, we discovered that the internal data was not filtered to exclude international traffic, and that indeed the worldwide Media Metrix data lined up very well against the (worldwide) internal data.
At the IAB Leadership Forum, we broke into discussion groups to talk about the document. In my section, a gentleman who runs the internal analytics group at a leading publisher (who shall remain unnamed, but I get the newspaper they publish delivered at home each day), noted that internal data cannot be used to track duration. There is a "first page" issue and a "last page" issue. The first page issue pertains to one-page visits. Without a second event (like a second server call), site-centric data cannot assign duration to a single-page visit. And, comScore data show that there are an awful lot of single page visits. The last page issue is similar. On a multi-page visit, site-centric data can track duration, except for that accruing to the last page. There is generally no way to determine the end of the visit based on any observable trigger activity.
Consequently, as duration becomes more and more important to publishers and advertisers, I expect people-centric data to also become more important. Without measuring people, you can't really measure duration.
But, please, go to the IAB Web site and review the document for yourself. Be a part of the industry coalition that moves our collective understanding and use of research forward.