How Do You Get Impression-to-Sale Metrics for Clickbank Promotions?

I'm going to drop an ad on my site promoting a clickbank product. The idea is to split-test it against an adsense ad. The only problem is that all the tracking on Adsense is built-in. Just looking at the dashboard I can tell what my CTR is, what my CPC is, and what my CPM is.

How can you do something similar with clickbank? I feel like I'm going to have to do some strung-together scheme like checking the pageviews on google analytics and then dividing by two to account for the split test, and then open my CB control panel in another window, check the earnings for the same period as the analytics is showing, then do all the division manually to figure out what my CTR and CPC are.

I'm getting about $1.00 p/click now with a little better than a 1% CTR with Adsense, I'd like to see if I can do better with CB ads....but you can't tell if you can't track.

a) Use any of the free ad tracking systems that are available; or

b) Serve your clickbank ad in an iframe. In the page that sits in the iframe with the banner on it, increment a counter (just store the value in a plain text file) on every impression before you display the ad.