In an investigation of possible brain damage due to alcoholism, an X-ray procedure known as a computerized tomography (CT) scan was used to measure brain densities in 11 chronic alcoholics. For each alcoholic, a nonalcoholic control was selected who matched the alcoholic on age, sex, education, and other factors. The brain density measurements on the alcoholics and the matched controls are reported in the accompanying table.20

(a) What is the value of the Wilcoxon signed-rank test statistic for comparing the means?
(b) The P-value for the Wilcoxon signed-rank test is 0.0049. If α = 0.01, what is your conclusion regarding H0?

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