Question 12.51

For Exercises 51–54, use the Crash data set, which contains information about the severity of injuries sustained by crash dummies when the National Transportation Safety Board crashed automobiles into a wall at 35 miles per hour.

Question 12.51

crash

51. Head Injuries and Vehicle Size. The variable head_inj contains a measure of the severity of the head injury sustained by crash dummies. The variable size2 categorizes the type of vehicle, such as light, medium, heavy, pickup truck, MPV (SUV), and so on. The values of the variable size2 are as follows: 1 = compact car, 2 = light car, 3 = medium car, 4 = heavy car, = = minicompact car, 6 = van, 7 = pickup truck, and 8 = MPV (SUV). Would you expect the population mean severity of head injuries suffered by the dummies to be the same across all the size categories? Use technology to perform the analysis of variance, using . Comment on the results.

12.1.51

.: Not all the population means are equal. Reject if the . . Since the is , we reject . There is evidence that not all the population means are equal.