Polyunsaturated fatty acids in the diet favorably affect several risk factors for cardiovascular disease. The principal dietary polyunsaturated fat is linoleic acid. To test the effects of dietary supplements of linoleic acid on blood pressure, 17 adults consumed 23 g/day of safflower oil, high in linoleic acid, for 4 weeks. Blood-pressure measurements were taken at baseline (before ingestion of oil) and 1 month later, with the mean values over several readings at each visit given in Table below.

Subject Baseline SBP 1-month SBP Baseline minus 1-month SBP
1 119.67 117.33 2.34
2 100.00 98.78 1.22
3 123.56 123.83 -0.27
4 109.89 107.67 2.22
5 96.22 95.67 0.55
6 133.33 128.89 4.44
7 115.78 113.22 2.56
8 126.39 121.56 4.83
9 122.78 126.33 -3.55
10 117.44 110.39 7.05
11 111.33 107.00 4.33
12 117.33 108.44 8.89
13 120.67 117.00 3.67
14 131.67 126.89 4.78
15 92.39 93.06 -0.67
16 134.44 126.67 7.77
17 108.67 108.67 0.00

1. What parametric test could be used to test for the effect of linoleic acid on SBP?
2. Perform the test in Problem 1, and report a p-value.
3. What nonparametric test could be used to test for the effect of linoleic acid on SBP?
4. Perform the test in Problem 3 and report a p-value.
5. Compare your results in Problems 2 and 4, and discuss which method you feel is more appropriate here.