Question

A weight-lifting coach claims that a weight-lifter can increase strength by taking vitamin E. To test the theory, the coach randomly selects 9 athletes and gives them a strength test using a bench press. The results are listed below. Thirty days later, after regular training supplemented by vitamin E, they are tested again. The new results are listed below. Find the test statistic for a Wilcoxon signed-rank test to test the claim that the vitamin E supplement is effective in increasing the athletes' strength.

Athlete: 1,2,3,4,5,6,7,8,9,

Before: 246,199,219,260,275,206,214,223,247

After: 256, 204,219,258,282,221,211,218,252

Answer 1