the direct-to-consumer shopping website abc wants to add a coupon box to the checkout page (see the example of a coupon box below), but the marketing team worries that adding a coupon box will cause users who don't have coupons to abandon their shopping basket. the team designs an experiment with the treatment being whether the user sees the coupon box on the checkout page. the experiment randomizes at the user level. the experiment will run for a week, and the experiment sample is a random set of customers who have browsed the website during the week. no actual coupon is issued, and the team will track the dollar amount spent per user during the week of the experiment.