The cost of automobile insurance varies by location, ages of the drivers, and type of coverage. The following are estimates for the annual 2006–2007 premium for a single male, licensed for 6–8 years, who drives a Honda Accord 12,600 to 15,000 miles per year and has no violations or accidents. These estimates are provided by the California Department of Insurance for the year 2006–2007 on its website (http://www.insurance.ca.gov).

a. What type of design was used in collecting these data?

b. Is there sufficient evidence to indicate that insurance premiums for the same type of coverage differs from company to company?

c. Is there sufficient evidence to indicate that insurance premiums vary from location to location?

d. Use Tukey’s procedure to determine which insurance companies listed here differ from others in the premiums they charge for this typical client. Use α = .05.

e. Summarize your findings.