That comment was through my own observations and talking to other merchants. Let’s say you’re offering 20% off on product A - often what will happen is that the customer will buy product B as well with their “savings”. If product B is worth more than the saving, then the order size is bigger. Also, let’s say you have Product X at $240 and Product Y at $300 - if you offer a 10% discount coupon on Product Y, those who have have gravitated to X may switch to the more expensive item as they only need to spend a little more to get the “better” product - even though it may cost you the same or only slightly more. It’s horses for courses I guess, depends a lot on your margins and how you structure your pricing.

As I just started to look into this, I’m very curious to know how you’re statement “customers who use coupons tend to buy more or higher value goods” relates to what I’ve read. Seems contradictory, but maybe I’m not understanding?

http://www.tomhcanderson.com/2008/05/16/interesting-more-effective-and-creative-use-of-coupon-promotion/