Yesterday AdSense impressions dropped down for 15% on one of my best sites. In comparison to previous days with the same impressions (tracked by AWStats), the difference between page impressions was markedly high - 1:4 (AWStats page views: AdSense impressions).
The CPM is standard, just impressions are too low. Of course, this has reduced the revenue automatically for 15%.
I checked server logs, and server was up and fine all the time, and adsense on other websites on the same server received regular number of impressions in comparison to previous days with similar number of page views.
Impressions on other sites are fine, therefore AdSense servers didn't get down during that time ...
Does anyone else observed and experienced such fluctuations in AdSense impressions?