The Insurance Institute for Highway Safety regularly tests cars for various safety factors. In one such test, the institute tests the bumpers in 5-mile per hour (mph) crashes. The following data represent the cost of repairs (in dollars) after four different 5-mph crashes on small utility vehicles. The institute blocks by location of crash, and the treatment is car model.

(a) Normal probability plots for each treatment indicate that the requirement of normality is satisfied. Verify that the requirement of equal population variances for each treatment is satisfied.
(b) Is there sufficient evidence that the mean cost of repairs is different among the four SUVs at the a = 0.05 level of significance?
(c) If the null hypothesis from part (b) was rejected, use Tukey's test to determine which pairwise means differ using a familywise error rate of a = 0.05.

Transcribed Image Text:

Saturn VUE Jeep Cherokee Toyota RAV4 Hyundai Santa Fe Front into 652 416 489 539 flat barrier Rear into 824 556 1897 1504 flat barrier Front into 1448 1179 1151 1578 angle barrier Rear into pole 1553 1335 2377 1988