5.11 The conclusion in Problem 5.10 was that the median difference (Before minus After) was positive for the affected age group, but this does not imply that the reduction was the result of raising the minimum legal drinking age. Other factors, countermeasures, or advertising campaigns

[like MADD (Mothers Against Drunk Drivers)] may have affected the fatality ratios. In order to investigate further, these researchers compared the Before minus After ratios for the affected age group with the corresponding difference ratios for the 25–29 age group, who were not affected by the law change. Carry out an appropriate test and write a report of your conclusions.

State Affected Age Group 25–29 Age Group Florida 0.060 0.025 Georgia 0.068 0.023 Illinois 0.025 0.004 Iowa 0.078 0.008 Maine 0.022 0.061 Michigan 0.072 0.015 Montana 0.041 0.035 Nebraska 0.086 0.016 New Hampshire 0.012 0.061 Tennessee 0.035 0.051