You just saw a commercial for the Tread Master, an exercise machine that claims an average weight loss of 10 pounds. A commercial for the Climber, a competing product, claims that only 1 out of 10...

You just saw a commercial for the Tread Master, an exercise machine that claims an average weight loss of 10 pounds. A commercial for the Climber, a competing product, claims that only 1 out of 10 users of the Tread Master lost any weight at all. The rest of them gained weight. How can both of these claims be true?