Question

1. Does increasing the amount of calcium in our diet reduce blood pressure? Examination of a large sample of people revealed a relationship between calcium intake and blood pressure. The relationship was strongest for black men. Such observational studies do not establish causation. Researchers therefore designed a randomized comparative experiment. The subjects in part of the experiment were 21 healthy black men. A randomly chosen group of 10 of the men (from the 21) received a calcium supplement for 12 weeks. The control group of 11 men received a placebo pill that looked identical. The experiment was double-blind. The response variable is the decrease in systolic (top number) blood pressure for a subject after 12 weeks in mm of mercury. An increase appears as a negative response. Here are the data:

Treatment 7 -4 18 17 -3 -5 1 10 11 -2

Control -1 12 -1 -3 3 -5 5 2 -11 -1 -3

What is the 95% confidence interval for the difference between the treatment and control means? (i.e. treatment - control) Assume unequal population variances and the samples come from a normal distribution. From the confidence intervals given below, choose the one that most closely matches the one you calculated.

a. (-1.48077, 12.02622)

b. (-1.52343, 12.13294)

c. (-1.26100, 5.737200)

d. (-1.71204, 12.25749)

e. (-1.87884, 12.43484)

2. Consider the experiment and data from the above question. Did increasing the amount of calcium reduce blood pressure? Conduct the appropriate hypothesis test and use α = 0.05.

a. There is not enough evidence to conclude that increasing the amount of calcium reduced blood pressure.

b. There is enough evidence to conclude that increasing the amount of calcium reduced blood pressure.

Answer 1

1)

from above correct option is

d. (-1.71204, 12.25749)

2) a. There is not enough evidence to conclude that increasing the amount of calcium reduced blood pressure.