I want to talk about a recent experiment I did for one of my sites in relation to increasing Adsense CTR. Originally this site had two columns, a navigation column on the left, and a main content column. The only advertising on the site was Adsense (two blocks). Then, I started noticing that all the big, established sites have multiple ads on their pages, and I thought, why not do that on my site? So, I added a third column to that particular site, and that column is entirely advertising, consisting of 125×125 boxes and a 120×600 skyscraper. Those are mostly affiliate links.
Initially I had no idea how well this experiment was going to turn out. I actually made sure that the original files were carefully kept, so I can revert back to the original two-column layout at a moment’s notice. Fortunately, I haven’t had to do that. Based on two week’s worth of data, I was pleasantly surprised to find out that the average Adsense CTR improved by more than 10%. This, plus the extra income I received from all the other advertising, meant that the 3-column format is here to stay.
I believe this is because visitors are used to being on sites with multiple ads. It’s quite possible that when they land on a site that only has Adsense, they will spot these ads right away, and possibly steer away from it. At the same time, if the page they land on shows multiple advertising blocks, each ad by itself is no longer as conspicuous, and visitors will end up clicking on things that they find interesting.