If you're looking for one truth in online advertising, it's that there is no truth. At least that's what Bob Ivins, one of the leading men at Web measurement firm comScore Media Metrix says.
comScore is in the business of telling advertisers what they're paying for.
Just think of the sheer number of measurement options: Do you want to know page views, uniques, time spent,
hits, click-throughs, streams sessions, queries or engagement? There's a dizzying array of options by which advertisers can measure their spend. Problem is none of them paint a comprehensive
Page views used to be the gold standard of Web measurement, but thanks to the advent of XML or AJAX, which essentially makes it possible to run the equivalent of software within Web pages, options like user sessions, average time spent and "engagement" are in higher demand. Again, you'd need to measure all to get a comprehensive view of what users are doing on a given site--and even then, the individual measurements themselves aren't exact. For a medium that touts itself as the most measurable option for advertisers, there's still a long way to go.