BlogAds Study
Les Jones links to this study on BlogAds which concludes:
(1) the number of weekly page views (WPV) is a much stronger predictor of weekly ad revenue and price than are either the number of inbound links or the number of blogs providing those links
(2) the number of ads has a negative impact on ad price and a largely positive effect on ad revenue, and
(3) the political orientation of the blog matters: on average left-of-center blogs significantly out-earn their right-of-center counterparts.
I can say that once I got them rolling, I had no trouble selling them. In fact, I once had to refuse new ones because I had five on the main page already.
Regarding point number 3, a top spot on Kos goes for $5K per week. Wow. Of course, there are currently no ads in that spot.
