As part of a marketing campaign to increase customer spend and loyalty, eBay sent out coupons to 4000 buyers by post. Each buyer received one coupon for 10 which they could spend on eBay.co.uk in a two week window between the 4th and 17th August 2016. Some buyers used their coupon to get money off their purchases in that time (Redeemers) and others chose not to (Non-Redeemers). A third group of shoppers (Control) were not sent a coupon but will act as a benchmark as we assess whether the coupons successfully boosted customer spending as hoped Question: We calculate revenue as Revenue = Spend x Take Rate Assuming that Take Rate is 10% and that the cost of the coupon campaign is equal to the value of a coupon multiplied by the number of coupons redeemed, calculate the ROI of this campaign.