There is a big difference in performance when an ad appears in position #1 at the top of search results and when an ad appears in position #1 on the side.
Several months ago, Google’s Chief Economist Hal Varian wrote a post about understanding the average position metric, saying that “this distinction is important, since, on average, ads that appear above the search results tend to get substantially more clicks than ads that appear on the right-hand side.”
To help advertisers capitalize on that, Google last week announced its new “top vs. side” Adwords report segment. Advertisers can use the report to see how ads perform above and to the side of Google search results. While there may come a time when top vs. side targeting or bidding options are available, for now it is useful just to segment the data to help make bidding decisions and analyze comparative performance before and after changes.