Reconsider the previous three exercises.
a. Describe what power means in this study.
b. Would you expect that you could increase the power of a test by using a larger sample size or a smaller sample size? Explain.
c. Would you expect that using a smaller (more strict) significance level would increase or decrease the power of a test? Explain.
d. Would you expect that a larger difference between the groups would increase or decrease the power of a test? Explain.

Data from previous exercises

The Nellie Mae organization conducts an extensive annual study of credit card usage by college students. For their 2004 study, they analyzed credit bureau data for a random sample of 1,413 undergraduate students between the ages of 18 and 24. Th ey found that 76% of the students sampled held a credit card. Three years earlier they had found that 83% of undergraduates sampled held a credit card. (Assume that the sample size was similar in 2001.)