Eight human molar teeth were sliced in half. For each tooth, one randomly chosen half was treated with a compound designed to slow loss of minerals; the other half served as a control. All tooth halves were then exposed to a demineralizing solution. The response is percent of mineral content remaining in the tooth enamel.

The data are given in Table 14.12.

(a) Perform the Wilcoxon signed rank test to determine whether the treatment maintained a higher mineral content in the enamel.

(b) Compute the paired t statistic and compare the results. Comment on the differences in the results.

Table 14.12 Data for Exercise 5. Mineral Content Control 66.1 79.3 55.3 68.8 57.8 71.8 81.3 54.0 Treated 59.1 58.9 55.0 65.9 54.1 69.0 60.2 55.5