Just read this on Google's site: QUOTE Don't believe the myth about blocking 'low-paying advertisers' Our auction system automatically selects the best performing ads for each page to help you earn the most possible money. This is especially true with our new expanded text ads. By filtering ads you think are low paying, you could actually be cutting out the most optimized ads and decreasing your revenue potential. Each ad that is filtered is one less bid in the auction, lowering the price for the winning ad on your site. You benefit most when there is a larger pool of advertisers competing for a place on your site. Additionally, when we calculate the auction, we take ad clickthrough rates (CTR) into account - an ad with a $0.25 cost-per-click (CPC) with a 5% CTR is more valuable than an ad with a $1.00 CPC but a 0.1% CTR. UNQUOTE One small question.. is the CTR that is considered is the CTR for that particular publisher or overall CTR for that ad for all publishers ????
The second. And AWA conceded at webasmasterwold that it isn't necessarily true. He said if you start blocking to do a full week text, don't rely on a day or a few hours. But that you could conceivably improve ctr. In my tests I did improve CTW by 10-20%. eCPM is somewhat improved too. We're not talking a ton of money though.