Let us suppose that you are a seller of toothpaste to the grateful masses, and let us suppose that your toothpaste comes in a five-ounce tube, which is packaged in a cardboard box. How can you convince the wary consumer in the store that your toothpaste is a bargain?
Yes, that should do it: “25% FREE.” You are not just getting five ounces of toothpaste: you are getting one more ounce than you would if you bought four ounces at the same price. This is time-honored marketing logic.
Now let us suppose the bean-counters have counted their beans and come up one bean short, and it is determined that your company will sell tubes of toothpaste in a cardboard box of exactly the same dimensions, but with only four ounces inside instead of five. How will you, the marketer, label these boxes to show at a glance that, though they occupy the same space on the shelf, they have less toothpaste inside?
