• by October 27, 2000

I've lamented the inaccuracies of measuring Internet ad spending in the past, and I'm surely not alone in my frustration. The range of web ad spending totals for the first half of 2000 is, to say the least, confusing - from IDC's $2.4 billion, to the IAB's $4.1 billion, to AdZone's $6.3 billion - so what's a media buyer to do? How do you figure out the average CPMs?

For 2000, AdKnowledge estimates the current average CPM to be about $34, which to me seems unreasonably high.

I'm not alone. eMarketer recently examined all of the above predictions and came up with a much more reasonable first half of 2000 total - $2.6 billion - and a much more reasonable average CPM.

They even dared to go against the venerable IAB, stating that the IAB numbers are too high, and must be reduced to take account of barter transactions and errors in its methodology: self-reporting by advertisers, and extrapolation of their survey readership.

Honesty aside, there are many other sources of error in attempting to measure the average CPM, the report states, taking particular aim at basing predictions on published rate cards. "Rate cards for CPMs are routinely discounted; by how much, no one knows," the report says. "Estimating spending on Internet advertising using rate cards can create wildly inflated results."

eMarketer's estimate of first-half spending is well below most estimates, so applying that difference to the reported average CPM of $34, we would come up with an actual effective average industry-wide CPM of $14.40. (Check out their website - www.eMarketer.com - if you're interested in the formula.)

And yes, you can take that number straight to the negotiating table.