coachm - 6:19 pm on Jan 17, 2008 (gmt 0)

I think ypu're supposed to use Google Analytics to track conversions. But since many advertisers don't use that, apparently Google has other secret methods to determine ROI.

The ability to track conversion/ROI is built into ADwords. You can also use Google Analytics to get more detailed information, but it's not necessary.

If you search around here, you'll find that a LOT of advertisers flat out refuse to use either and both because they don't want to share their proprietary sales and profit information with google.