Rework the election data reported in Exercise 10-85 using the alternate CI procedure described in this section. Compare the lengths of the CI from Exercise 10-85 with this one. Discuss the possible causes of any differences that you observe.

Exercise 10-85

In the 2004 presidential election, exit polls from the critical state of Ohio provided the following results: For respondents with college degrees, 53% voted for Bush and 46% voted for Kerry. There were 2020 respondents. 

(a) Is there a significant difference in these proportions? Use α = 0.05. What is the P-value?

(b) Calculate a 95% confidence interval for the difference in the two proportions and comment on the use of this interval to answer the question in part (a).