The test–retest method is one way of establishing the reliability of a test. The test is administered, and then, at a later date, the same test is readministered to the same individuals. The correlation coefficient is computed between the two sets or scores. The following test scores were obtained in a test–retest situation.

First Score 75 87 60 75 98 80 68 84 47 72 Second Score 72 90 52 75 94 78 72 80 53 70 Find r and set a 95% confidence interval for .