There haven’t been any big studies on the impact of PPC, AdWords ads, on organic click through rates since Google dropped ads from the right rail in February. But a new small test has one advertiser saying their click through rates on their number one listings drop 15 points when their ads show, that is a CTR of 35% dropping to 20% when their ads show.

A WebmasterWorld thread has the details where vlexo who works at a “well known brand in the UK,” said he tested it after the right hand rail went away. He said when they increase their ad spend with Google, their number one listings drop in CTR from 35% to 20%.

He wrote:

He added, “I also picked keywords where we ranked in position 1 consistently throughout both a control period and the test period.”

Other past studies showed that this would not be the case, but those studies were done when there were ads on the right rail. Now there are only ads at the top and bottom.

Are you surprised by these results?

Forum discussion at WebmasterWorld.