Forum Moderators: skibum
I put their javascript on a basket page, though if you are not using a basket you could incorporate a temporary page with a redirect that would do the job.
The conversion rate won't equal the number of items purchased, but if you can work out generally what percentage of people go from clicking the more info button to making a sale, then the conversion info from Google can be used in conjunction to work out your estimated earnings per click.
you can check conversion rates by logging into Amazon's associates site (associates.amazon.com). It sometimes takes a while to update the previous day's statistics, though. In fact, I haven't been able to get my stats yet. :P
Usually it's pretty good about updating, though it sometimes takes as late as 10:00 AM or later (Eastern) to see them.
You can see percentages by link type by selecting view reports and scrolling down past the item sales summary.