3. "Users report 23 percent fewer cavities with Doakes' toothpaste,\" the large advertisement says. These results, you find, come from a reassuringly 'independentr laboratory, and the account is certified by a chartered accountant. Yet if you are not outstandingly gullible or optimistic, you will recall from experience that one toothpaste is seldom much better than any other. Then how can the Doakes people report such results? (Them lying is not an acceptable answer, and you have to say more than " chance error. ")