I noticed that removing a couple ad units from my page significally increased my revenue, even though the total CTR got lower as a result of this. I used to have a skyskraper on the left that normally shows 4 ads, and a large rectangle on the right in articles with also 4 ads normally showing. I removed the skyscraper completely, and reduced the large rectangle to a smaller one that only shows 3 ads. So now I only got that one ad unit on the page, in addition to a banner on the very bottom of every page. Seems this has helped by removing low paying ads and only displaying the high paying ones so whenever a user clicks and ads its sure to be an high paying one. Even though this reduced the CTR by more than half, it still increased the income with more than the double.
That is probably a situation of you having your skyscraper as the ad unit with the highest paying ads because it was the first ad unit that appeared in your page source code, and it's likely you had the 4 highest paying ads in that unit. But unfortunately when you do this the CTR on most skyscrapers isn't as high as rectangle units that are placed above the main content which is receiving loads of hits but on low paying ads. So when you removed the skyscraper which was receiving the highest paying ads those ads were move into the rectangle unit because that became the first ad unit in your source code, and because that ad unit was getting more clicks your earnings went up significantly because now the majority of your clicks are on your highest paying ad unit. So the moral of the story is you want to make sure that your ad units that receive the highest CTR are the ones that also have your highest paying ads, which is the ad unit that appears first in your source code. Now that said your left hand navigation bar is also a place that generally gets good visitor attention but generally not as much as a rectangle ad unit above your main content, so to make use of the area without bringing down your overall AdSense earnings you might look to integrating some affiliate products. That way you can still earn from this high lucrative position but also keep your highest paying AdSense ads in the high CTR ad unit.
Thanks for the tip. I actually placed a referal unit for firefox where i used to have the skyscraper, as well as a link unit. Btw, do you know if link units affect the price of other ad units on the site the same way? And if so, do you think i should remove the link unit again and only keep the rectangle?
Well in my experience Link Units don't effect earnings because they work slightly differently from the AdSense units in that they don't display advertiser ads unless they are clicked. So I would say leave your Link Unit, but that said what you might like to do is leave things for say a week as is - then after that week remove the link unit to see if you see any noticeable changes. I mean the best way to find out anything is just to test - and often the advice flowing around here at DP should be taken as a VERY general guide because many niches are very different, I mean in regards to you skyscraper issue that is a situation where if you have a VERY competitive industry where there are 10 - 20 advertiser all competing with very similar bid prices it may not make the world of different removing that skyscraper because all the ads on your page will be earning a similar EPC/CPC. Whereas if you have a less competitive industry where advertisers are paying vastly different amounts or there aren't many of them you might find that there are 3 main advertisers paying good money and 10 others that are paying a couple of cents per click in which case you want to make sure that those 3 main ones are in the high CTR unit. So it all varies from niche to niche. That said if you do find anything interesting with your Link Units and their effects on you overall earnings make sure that you share the insights here at DP so other people can test for themselves as well.
Burta: Thanks a lot for your valuable information, i see you know your share about adsense I will run with the current layout for a week or so as you suggest, and see what will be the results when removing the link unit again for 1 week more.
bettyswollocks: just remember to put the ad unit that gets highest CTR on top, and remove the one that gets lower ctr. First I did the mistake and actually kept my skyscraper, and removed the rectangle which had higher ctr
i have noticed that with less ads, i get the SAME CTR and less clicks... soi dont think its working for me