A medical researcher wanted to determine the effectiveness of coagulants on the healing rate of a razor cut on lab mice. Because healing rates of mice vary from mouse to mouse, the researcher decided to block by mouse. First, the researcher gave each mouse a local anesthesia and then made a 5-mm incision that was 2 mm deep on each mouse. He randomly selected one of the three treatments and recorded the time it took for the wound to stop bleeding (in minutes). He repeated this process two more times on each mouse and obtained the results shown.

(a) Explain how each mouse forms a block. Explain how blocking might reduce variability of time to heal.
(b) 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.
(c) Is there sufficient evidence that the mean healing time is different among the three treatments at the a = 0.05 level of significance?
(d) If the null hypothesis from part (c) was rejected, use Tukey's test to determine which pairwise means differ using a familywise error rate of a = 0.05.
(e) Based on your results for part (d), what do you conclude?

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Experimental Drug 1 No Drug Mouse Experimental Drug 2 3.2 3.4 3.4 4.8 4.4 3.4 6.6 5.9 5.4 4 6.5 6.3 5.2 6.4 6.3 6.1