After exercise, massage is often used to relieve pain, and a recent study shows that it also may relieve inflammation and help muscles heal. In the study, 11 male participants who had just strenuously exercised had 10 minutes of massage on one quadricep and no treatment on the other, with treatment randomly assigned. After 2.5 hours, muscle biopsies were taken and production of the inflammatory cytokine interleukin-6 was measured relative to the resting level. The differences (control minus massage) are given inTable 4.13.

(a) Is this an experiment or an observational study? Why is it not double blind?
(b) What is the sample mean difference in inflammation between no massage and massage?
(c) Wewant to test to see if the population mean difference μ_D is greater than zero, meaning muscle with no treatment has more inflammation than muscle that has been massaged. State the null and alternative hypotheses.
(d) Use StatKey or other technology to find the p-value from a randomization distribution.

(e) Are the results significant at a 5% level? At a 1% level? State the conclusion of the test if we assume a 5% significance level (as the authors of the study did).

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0.6 4.7 3.8 0.4 1.5 -1.2 2.8 –0.4 1.4 3.5 -2.8