Question

A randomized comparative experiment gave one group of 11 black men a calcium supplement for 12 weeks. A control group of 11 black men received a placebo that appeared identical. The table below gives the decrease (an increase appears as a negative entry) in seated systolic blood pressure (in mm of mercury) for all subjects at the beginning and end of the 12 week period.
Calcium Group 8 -3 24 18 2 -1 8 12 14 5 -25
Placebo Group -1 12 1 -3 3 -5 5 -2 -11 -1 -3

Does this evidence indicate that adding calcium to the diet of black men reduces seated systolic blood
pressure? Be sure to explicitly check all assumptions needed in the techniques you employ.

Answer 1

Ans. We use R to test the hypothesis and also normality assumption:-

QQplot for normality in paired differences:-

By QQplot for paired diffrences, we can say that data comes from Normal distributuion.

Hence, we can use paired t-test for differences.

Conclusion:-

There is insufficient evidence to support the claim that adding calcium to the diet of black men reduces seated systolic blood pressure.