While there are several caveats (such as the fact that they had to rely on average position, instead of examining each position in each auction each ad is a part of), the results are interesting:
We have used a statistical model to account for these effects and found that, on average, there is very little variation in conversion rates by position for the same ad. For example, for pages where 11 ads are shown the conversion rate varies by less than 5% across positions. In other words, an ad that had a 1.0% conversion rate in the best position, would have about a 0.95% conversion rate in the worst position, on average. Ads above the search results have a conversion rate within ±2% of right-hand side positions.
So what does that mean? It means it’s even more important to get your ad copy right—and maybe a little less important than we thought to have the highest position (by virtue of bid and quality score).
However, it’s important to note that this data is about conversion rate. Lower-positioned ads typically see fewer clicks, and fewer conversions. The rate may be the same overall, but an ad with a higher position will get more clicks and more conversions, even if the same percentage is converting.
What do you think? Have you seen better conversion rates from keywords you have a top position for, or is your conversion rate fairly steady for a single ad?