Inside Adwords had an interesting post a few days back about conversion rates and ad positions. Check it out if you missed it.

“We have used a statistical model to account for these … 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…”

Read more… Conversion rates don’t vary much by position.