Yup, there are stats here: http://ux.stackexchange.com/questions/11363/do-promo-...

		mijustin on Aug 13, 2013 \| parent \| context \| favorite \| on: This coupon code is a slap in the face Yup, there are stats here: http://ux.stackexchange.com/questions/11363/do-promo-codes-o... "In one usability test, removing the coupon code field increased overall conversion from 3.8% to 5.1% (an increase of 34%)."