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?

Use the Wilcoxon signed-ranks test to conduct the required test.

Would you recommend the Wilcoxon signed-ranks test over the Sign-test?

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