Question

A medical researcher is studying the effects of a drug on blood pressure. Subjects in the study have their blood pressure taken at the beginning of the study. After being on the medication for 4 weeks, their blood pressure is taken again. The change in blood pressure is recorded and used in doing the hypothesis test. Change: Final Blood Pressure - Initial Blood Pressure The researcher wants to know if there is evidence that the drug affects blood pressure. At the end of 4 weeks, 31 subjects in the study had an average change in blood pressure of -2.7 with a standard deviation of 5.3. Find the p -value for the hypothesis test.

Answer 1

Given that, n = 31

Let d = Final Blood Pressure - Initial Blood Pressure

Average change in blood pressure = -2.7 and

standard deviation (Sd) = 5.3

The null and alternative hypotheses are,

H0 : μd = 0

Ha : μd ≠ 0

This test is two-tailed test.

Test statistic is,

=> Test statistic = t = -2.836

Degrees of freedom = 31 - 1 = 30

Using Excel we find the p-value as follows :

Excel Command : = TDIST (2.836, 30, 2) = 0.0081

=> p-value = 0.0081