I could be mistaken but I believe some people said that they use Google Analytics to track what keywords people typed in when they made certain affiliate sales. I don't see how this can be done so please fill me in.
you cant track aff stats unless the merchant is going to install your analytics tag on their conversion page (which is unlikely)
It's not unlikely for the merchant to place your google tracking code (not related to analytics) on their sales page. You get this code in tools - conversion tracking - make sure it's set to https instead of http - (most merchants require that). If you dont' want to use google, or the merchant does not allow that, you'll need to use some type of software like Tracking202.com or AdTracker (I think that's the name) Good luck