2.14 Are highways getting safer? How can we begin to measure possible improvements in the travel by motor vehicle? One possibility is to study traffic safety data for any discernable patterns or trends.

The motor vehicle death rates per 100 million miles driven in the 50 states plus the District of Columbia are listed in Table 2.11 (U.S. National Highway Safety Traffic Administration, Traffic Safety Facts, annual (http://www.nhtsa.dot.gov/

people/Crash/Index.html).

a Construct a scatterplot of the 2002 data versus the 1980 data. Describe the pattern.

Which point deviates most extremely from the pattern?

b Are there any interesting clustering patterns among the states?

c What feature of the plot will help you say something about the improvement in highway safety over these years?