A researcher is told that she needs 90 subjects to attain 80% power (a = 0.05) to detect a true risk difference of at least 20% between two study arms. Use this information to answer questions 14-16. Question 14 2 pts She could set alpha at 0.01 to increase the power. 0 True False Question 15 2 pts She would need more than 90 subjects to detect a true risk difference of at least 15% between the two study arms, keeping the power at 80%. True 0 False Question 16 2 pts If she is able to enroll 120 subjects, she would have more than 80% power to detect a true risk difference of at least 20% between the two study arms. True 0 False