With the AMS statistics panel, you can examine how effective your adbars are by comparing how many times a banner has been displayed to how many times it has been clicked on. AMS automatically compares the two for you, with what's called a "click-through to exposure ratio".
To run this comparison, log into the ams_stats.cgi using the same username/password combination that you use to log into the administration panel (or you can log into the administration panel, then click on the link at the bottom that says "AMS Statistics System"). The location of the ams_stats.cgi script is in the same directory as your administration panel, which in many cases will be:
/cgi-bin/ams/ams_stats.cgi
Once logged in, you will see a panel that says "Advertiser Comparison". If you select "By Exposures", the adbars will be listed in order of number of exposures. If you select "By Click-Throughs", the adbars will be listed in order of the number of times each has been clicked on. These statistics are good to know, but don't show the effectiveness of the adbar until you compare the two. The last option, "By Click-Through to Exposure Ratio" does just that, gives you a comparison in percentages.
Select "By Click-Through to Exposure Ratio" and click on the "Show Comparison" button. The adbars are displayed in order of percentage for that month, highest being at the top. Once your adbars have been running for a while, you'll be able to get a good idea of how each one is doing. If you have adbars that have been running for over a month, you can also look at the "Total" column to see how well they've done overall.
Try comparing what's different about the adbars that are doing really well to the ones that aren't. You might be able to come up with some strategies for making adbars on your site more effective. Here are some general tips that may help: