Google's Chief Economist
Dan Friedman Hal Varian and his team have conducted research on whether ad position affects conversion rate. Their conclusion is that it doesn't much. I have a feeling "much" is subjective among SEMs.
Their research showed that for search results pages with 11 sponsored ads, conversion rates "only" varied 5% from first place to last. So, if an ad gets a 1% conversion rate in the first place, the worst it would get is 0.95%.
Friedman Varian wanted to emphasize that ad position is affected by ad quality. Therefore, ads with higher ad position are likely better quality and more likely to have higher conversion rates. In other words, don't compare apples to oranges when testing ad position. You would need to test the same ad across various positions.
What do you think of
Friedman's Varian's research on the correlation between conversion rate and ad position? Do you agree with his findings? Should a 5% variance really be considered low? Tell us your thoughts in the comments. (Comment position is first-come, first-served.)