Researchers developing new drugs must be concerned with possible side effects. They check a new medication for arthritis to be sure that it does not cause an unsafe increase in blood pressure. They measure the blood pressures of a group of 12 subjects, then administer the drug and recheck the blood pressures one hour later. The drug will be approved for use unless there is evidence that the drug causes an increase in average blood pressure of more than 20 points. They will test the hypothesis using .