10.37 Surgery versus placebo for knee pain Refer to Example 10, “Arthroscopic Surgery.” Here we show MINITAB output comparing mean knee pain scores for the placebo (Group 1) to lavage arthroscopic surgery

(Group 2) assuming equal population standard deviations.

a. State and interpret the result of the confidence interval.

b. Is it reasonable to assume equal population standard deviations?

c. State all steps and interpret the result of the significance test.

Sample N Mean StDev SE Mean 1 60 51.6 23.7 3.1 2 61 53.7 23.7 3.0 Difference = μ(1) − μ(2)

Estimate for difference: −2.10 95% CI for difference: (−10.63, 6.43)

T-Test of difference = 0(vs •):

T-Value = −0.49 P-Value = 0.627 DF = 119 Both use Pooled StDev = 23.7000