I have a sports site. It was making like $0.75 per click for couple of months. Now suddenly, average CPC has dropped to $0.5 or even $0.4. Sometimes, I even see $0.2 or $0.08 per click.
Is there an option to set minimum CPC for your ads as a publisher? I can't find it anywhere on AdSense but competitors like Adbrite seem to have it.
A Google AdSense publisher does not have the control over the ads that are shown in your website. You may block specific category of ads.
You need to understand that advertisers are expecting conversions for every click that you are sending them. They may have set daily limits and even monthly limits. When their budgets run out, your only option is to display cheaper ads, which explains the lower CPC.
You have absolutely no control over your earnings as an AdSense member and publisher of AdWords ads. The advertisers set the CPC. Google shares the click revenue with you as a publisher. Google does not tell you the % you earn per click on any advertisement.
The decline in your estimated earnings per click is only due to different ads displaying by different advertisers who have bid different prices per click. Pageviews as nothing to do with the price per click that you earn.
May be clicks on your site are not converting causing AdSense to display cheaper ads. So you can't do anything about it. So if you can change the type of audience (eg middle class to upper class, student to middle aged etc) - that could change the conversion factor.
What about the CPC in the peak business hours?
Ensuing account suspension could cause fall in CPC though, I hope this is not the case with you.
As far as I know Google lets advertisers to place ads on a specific web site rather than the whole network. If that's the case it is possible to adjust bid for that specific site.
However it is also possible that your declining cpc could be caused by declining pageviews. It could even be possible that advertiser discovered a low competition for keywords and adjusted his bids accordingly.
