It has been claimed that a small machine that releases negative ions into the air in the bedroom enhances natural sleep.

a. Ten people try the machine for one night and nine say that they slept better and one person says she slept worse. Do you believe that the presence of the machine enhances sleep?

b. If thirteen people had tried the machine and nine had slept better, one worse, and three didn't find any difference, would you believe that the presence of the machine enhances sleep?

c. If one-hundred ten people had tried the machine and sixty-five had slept better, thirty worse, and fifteen didn't find any difference, would you believe that the presence of the machine enhances sleep? POLI967