Chi-square test of independence
Suppose we have a dataset of observed vehicle crashes in the state of Texas in 2021, Restraint Use by Injury Severity and Seat Position (https://www.txdot.gov/data-maps/crash-reports-records/motor-vehicle-crash-statistics.html), and want to know whether using a seat belt resulted in a statistically significant difference in fatalities. We have the table of observed values as follows:
Restrained |
Unrestrained |
Total |
|
Fatal |
1,429 |
1,235 |
2,664 |
Not Fatal |
1,216,934 |
22,663 |
1,239,597 |
Total |
1,218,363 |
23,898 |
1,242,261 |
Figure 5.6 – Chi-square...