The following data come from a study designed to investigate drinking problems among college students. In 1983, a group of students were asked whether they had ever driven an automobile while drinking. In 1987, after the legal drinking age was raised, a different group of college students were asked the same question Drove While Drinking 1983 1987 Total
Yes 1250 991 2241
No 1387 1666 3053
Total 2637 2657 5294

Required:
a. Use the chi-square test to evaluate the null hypothesis that the population proportions of students who drove while drinking are the same in the two calendar years.
b. What do you conclude about the behavior of college students?
c. Again test the null hypothesis that the proportions of students who drove while drinking are identical for the two calendar years. This time, use the method based on the normal approximation to the binomial distribution that was presented in Section 14.6. Do you reach the same conclusion?
d. Construct a 95% CI for the true difference in population proportions.