10. Interpreting Display for Test with Before After Treatment Results Captopril is a drug designed to lower systolic blood pressure. When subjects were tested with this drug, their systolic blood pressure readings (in mmHg) were measured before and after the drug was taken. Excel was used to conduct a t test using the matched pairs of before after readings, and the results are shown below (based on data from “Essential Hypertension: Effect of an Oral Inhibitor of Angiotensin-Converting Enzyme,” by MacGregor et al., British Medical Journal, Vol. 2). Use the Excel results to test the claim that captopril is effective in lowering systolic blood pressure. Is it effective?

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d, x 2 5 7 1 1 y 2 3 9 4 0 x 8 8 5 2 7 3 y 9 6 5 5 3 8 Excel 9-4 Inferences from Matched Pairs 491