Drugs. In a full-page ad that ran in many U.S. newspapers in August 2002, a Canadian discount pharmacy listed costs of drugs that could be ordered from a website in Canada. The table compares prices (in US$) for commonly prescribed drugs.
a) Give a 95% confidence interval for the average savings in dollars.
b) Give a 95% confidence interval for the average savings in percent.
c) Which analysis do you think is more appropriate? Why?
d) In small print the newspaper ad says, "Complete list of all 1500 drugs available on request." How does this comment affect your conclusions above?