Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying table (based on data from “Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme”, by MacGregor et al., BMJ, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril has an effect on systolic blood pressure? i) Use the Wilcoxon signed-ranks test to conduct the required test without using "wilcox.test" function in R. Please state the hypothesis, provide the p-value, and the conclusion in the context of the problem. ii) Use the Wilcoxon signed-ranks test to conduct the required test using "wilcox.test" function in R. Please present a screenshot of the R output of your call to the function wilcox.test. iii) Would you recommend the Wilcoxon signed-ranks test over the Sign-test? Please explain reasoning.

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Captopril is a drug designed to lower systolic blood pressure. When subjects were treated with this drug, their systolic blood pressure readings (in mm Hg) were measured before and after the drug was taken. Results are given in the accompanying table (based on data from “Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme”, by MacGregor et al., BMJ, Vol. 2). Using a 0.01 significance level, is there sufficient evidence to support the claim that captopril has an effect on systolic blood pressure?

i) Use the Wilcoxon signed-ranks test to conduct the required test without using "wilcox.test" function in R. Please state the hypothesis, provide the p-value, and the conclusion in the context of the problem.

ii) Use the Wilcoxon signed-ranks test to conduct the required test using "wilcox.test" function in R. Please present a screenshot of the R output of your call to the function wilcox.test.

iii) Would you recommend the Wilcoxon signed-ranks test over the Sign-test? Please explain reasoning. 

Subject
Before
After
Difference
Sign
Rank
Signed Rank
J
155
A B C D E F G H | I
200 174 198 170 179 182 193 209 185
191 170 177 167 159 151 176 183 159 145
-21 -3 -20 -31
-9
-4
-17 -26 -26 -10
3
-3
2
-2
-
7
-7
1
-1
6
-6
-
11
-11 -5
5 9.5 9.5
-9.5
K L
169 210
146 177
-23 -33
4 8 12
-8
-12
-9.5-4
Transcribed Image Text:Subject Before After Difference Sign Rank Signed Rank J 155 A B C D E F G H | I 200 174 198 170 179 182 193 209 185 191 170 177 167 159 151 176 183 159 145 -21 -3 -20 -31 -9 -4 -17 -26 -26 -10 3 -3 2 -2 - 7 -7 1 -1 6 -6 - 11 -11 -5 5 9.5 9.5 -9.5 K L 169 210 146 177 -23 -33 4 8 12 -8 -12 -9.5-4
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