7.127 Two-sample t test versus matched pairs t test, continued. Refer to the previous exercise. Perhaps an easier way to see the major difference in the two analysis approaches for these data is by computing 95% confidence intervals for the mean difference.

1. (a) Compute the 95% confidence interval using the two-sample t confidence interval.

2. (b) Compute the 95% confidence interval using the matched pairs t confidence interval.

3. (c) Compare the estimates (that is, the centers of the intervals) and margins of error. What is the major difference between the two approaches for these data?