The Scroll Bar Theory
When I first started using AdSense one of the tips that some AdSense experts suggested was to run skyscrapers down the right hand side of your site because this is where readers eye would be drawn to when they went to use the scroll bar.
Of course this strategy became less and less effective (probably due to rise in scroll wheels on the mouse which means less and less people use the scroll bar).
The Tabbed Browsing Theory
Today I was came across a suggestion by Chris Kenworthy who had a tip that reminded me of the above strategy. He’s been experimenting with running horizontal AdSense adlink units across the very top of his site. He’s tracked how much readers using different browsers click on the adlinks and has found that those using FireFox and IE7 (both with tabbed browsing – I presume it’d be similar with Safari) click the adlink units three times as much as others.
The reason for the increased clicks is similar to the scroll bar theory. People with tabbed browsing look at the top of their browsers to see the tabs and in doing so see the adlinks.
The adlink unit is ideal for this as it’s such a narrow ad but it would also be interesting to see if the CTR on larger banner ads also is higher with people using tabbed browsing.