Forecast and Actual Temperatures Refer to Data Set 10 in Appendix B and use all of the actual low temperatures and the low temperatures that were forecast one day earlier.

a. Using a 0.05 significance level, test the claim that there is no difference between the actual low temperatures and the low temperatures that were forecast one day earlier.

b. Construct a 95% confidence interval estimate of the mean difference between the actual low temperatures and the low temperatures that were forecast one day earlier.

c. Compare the results to those obtained in Exercise 19. Do the one-day forecast values appear to be better than the five-day forecast values?

8-4 Beyond the Basics