Refer to News Story 13 and the accompany­ing report on the book’s website, “2003 CASA National Survey of American Attitudes on Substance Abuse VIII: Teens and Parents.”
a. The margin of error for the teens and for the parents are reported in the news story. What are they reported to be?
b. Refer to page 30 of the Original Source 13 report. The margins of error are reported there as well. What are they reported to be? Are they the same as those reported in the news story? Explain.
c. The 1987 teens in the survey were asked, “How harmful to the health of someone your age is the regular use of alcohol—very harm­ful, fairly harmful, not too harmful, or not harmful at all?” Forty-nine percent responded that it was very harmful. Find a 95% confi­dence interval for the proportion of all teens who would respond that way.
d. The 504 parents in the survey were asked, “How harmful to the health of a teenager is the regular use of alcohol—very harmful, fairly harmful, not too harmful, or not harmful at all?” Seventy-seven percent responded that it was very harmful. Find a 95% confidence interval for the proportion of all parents (similar to those in this study) who would respond that way.
e. Compare the confidence intervals in parts (c) and (d). In particular, do they indicate that there is a difference in the population propor­tions of teens and parents who think alcohol is very harmful to teens?
f. Write a short news story reporting the results you found in parts (c) to (e).