Assignment:
Each year, the National Highway Traffic Safety Administration (NHTSA) together with the National Center for Statistics and Analysis (NCSA) publishes Traffic Safety Facts, which summarizes the motor vehicle traffic crash experience for the United States. Traffic Safety Facts 2001 includes trend data, crash data, vehicle data, and people data. Also, the NHTSA and NCSA publish a report summarizing the motor vehicle crash data of the 17 states in the NHTSA's State Data System.
In 2001, there were 42,116 fatalities in the United States as a result of motor vehicle crashes. The pie chart at the right shows the
national distribution of traffic fatalities with respect to age group. For example, 24% of all motor vehicle fatalities were young adults aged 16-24. Using the data from the 17 states in the NHTSA's State Data System as a sample, the contingency table shows the number of motor vehicle fatalities according to age and geographic location within the United States.
1. In 2001, how many people in the United States aged 16-24 died as a result of a motor vehicle crash?
2. Assuming the variables region and age are independent, in which region did the number of motor vehicle fatalities for the 16-24 age group exceed the expected number of fatalities?
3. Assuming the variables region and age are independent, in which region did the number of motor vehicle fatalities for the 25-34 age group exceed the expected number of fatalities?
4. At a = 0.05, perform a chi-square test to determine whether the variables region and age are independent. What can you conclude?
|
Eastern |
Central |
Western |
| under 16 |
503 |
361 |
654 |
| 16-24 |
2175 |
1555 |
2373 |
| 25-34 |
1460 |
934 |
1613 |
| 35-44 |
1494 |
1008 |
1527 |
| 45-54 |
1206 |
776 |
1225 |
| 55-64 |
733 |
469 |
739 |
| 65-74 |
637 |
411 |
594 |
| 75+ |
973 |
603 |
808 |
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| observed |
2175 |
1555 |
2373 |
| Expected |
536 |
504 |
711 |