Will your ad perform better on the top spot on the left or on the right? Sixth one up from the bottom?
When you link your Google AdWords and Google Analytics accounts, it will track performance of your ads with a lot of detail. One of the things it tracks, is performance by ad position.
Go to Traffic Sources » AdWords » Keyword Positions
In this report you can see all the familiar information such as impressions, clicks, CTR etc… The great thing about this report is the ability to segment by keyword and ad position. If you have Conversion Goals and E-Commerce Tracking set up you can see sales and revenue by ad position as well.
How Do I Know?
You will need to test your ad in a few positions for a couple of weeks each. Make sure you have enough representative data and then run the Ad Position report and see what has performed better.
Image Credit: danielbroche