The International Journal of Wildland Fire (December 2011) published a study of the time it takes to contain wildfires, both with and without aerial support. Containment time (in hours) was estimated by fire management personnel for a particular wildfire scenario that had no aerial support. Fire management personnel were classified according to one of three primary roles- ground, office, or air support. Data for 21 fire managers (simulated, based on information provided in the article) are listed in the table. One objective is to compare the estimated containment times of the three groups of fire managers.

a. Why is the ANOVA F-test of Chapter 9 inappropriate for analyzing these data? Use graphs to support your answer.
b. What is the appropriate nonparametric test to apply? State H0 and Ha for the test.
c. Rank the 21 estimated containment times, and then find the rank sums for the three groups of fire managers.
d. Compute the nonparametric test statistic.
e. Find the rejection region for the test using α = .10.
f. State the appropriate conclusion?

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Air Office Ground 7.6 10.8 20.9 15.5 9.7 5.4 2.8 3.9 5.9 4.3 2.5 3.4 2.7 2.8 3.6 5.9 4.6 2.6 3.3 3.2 7.7