Maybe all those A List blogs aren't quite as valuable as they hoped...

I don't know if you recall, but awhile ago 4/7 Media put up a post valuing the big A list blogs at many millions of $. The only problem was they were assuming CPM's in the $10-$30 per page range - we demurred, saying in our experience it was an order of magnitude lower.

Well, we were right of course (Sadly in a way, because Broadstuff was worth a tidy sum on those analyses) . Some published analysis shows the true picture, looking at pricing of remnant Ads (those filling unsold site inventory):

First, Andrew Chen (useful post, also describes how to guess CPM of a site, I'd broadly agree):

As a rough rule of thumb, I'd typically guess the following - these are very rough approximations, just to illustrate a couple points:

- Social sites (forums/chat/etc) without direct ad sales teams: <$0.25 CPM
- Largely international sites: <$0.50 CPM
- Medium-sized sites that use banner ad networks: <$1 CPM
- Reference sites in a specific category: >$5 CPM or sometimes much higher, depending on category
we ran into home improvement reference sites that did $20 CPMs

Because we were mostly dealing with so-called "remnant" advertising, these numbers are likely to be at the bottom of the range for these sites. That is, social networks might quote a CPM of $20 CPM, but what they really mean is that 1% of their inventory is sold at that, and the rest of the 99% is sold at <$0.25 prices.

Then TechCrunch:

Small sites (those with less than one million page views per month) command nearly three times as much per ad as large sites (those with more than 100 million page views per month): an effective CPM (cost per thousand) of $1.18 versus $0.38. The effective CPM across sites of all sizes is $0.49. All of these figures are for March, 2008. Ad rates are also growing faster for small sites, up 18 percent since January versus 12 percent growth overall.

The low average rates for large sites reflects the poor returns on social networks, entertainment, and gaming sites. Effective CPMs for social networks are amongthe lowest at $0.37 in March. But there is hope, that was up 69 percent from $0.22 in January.

That bit about smaller blogs doing well is very interesting to us ...

But Facebook's $15bn valuation looks a tad shaky on these CPM's - or at least you have to make some interesting assumptions......