• The Wall Street Journal, Friday, January 5, 2007 10:45 AM

The Internet is supposed to be the most quantifiable medium, but publishers don't keep track of users in a uniform manner, creating discrepancies everywhere. Even video can be hard to track.

Different video sites have different definitions for what constitutes a viewing. For instance, each click counts as a view at vSocial, a seller of premium video services to businesses, while at Revver--the video site that shares ad revenue with producers--a view is only counted if a user watches an entire clip and an ad that has to be downloaded at the end.

YouTube, the Web's most popular video destination according to many estimates, doesn't disclose how it keeps track of video views, much to the chagrin of the press and pundits like Mark Cuban, who openly questions the site's statistics. Matt Smith, a managing director at London-based Viral Factory, agrees. "We're not totally convinced by YouTube's tracking." He says spikes in views for certain videos present "some really weird anomalies."

Such anomalies don't just occur with video, of course. Gailik asks how Google, Yahoo and AOL compiled their year-end lists of the most popular search terms? That methodology is never the same; Google takes out references to its own sites and tracks how a particular term increases in popularity over time. Yahoo removes all company names, and generic terms (like "soccer"). As a result, there was almost a complete lack of overlap between the three lists.

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