A study by Bell (A-45) investigated the hypothesis that alteration of the vitamin D-endocrine system in blacks results from reduction in serum 25-hydroxyvitamin D and that the alteration is reversed by oral treatment with 25-hydroxyvitamin D3. The eight subjects (three men and five women) were studied while on no treatment (control) and after having been given 25-hydroxyvitamin D3 for 7 days (25-OHD3). The urinary calcium (mg/d) determinations for the eight subjects under the two conditions can be found in Question 40 on page 289 in the textbook.

What type of test is most appropriate for this study, a paired or independent samples t-test?

a: A paired t-test is most appropriate because the same subjects were measured twice, first without treatment and then after treatment, so the measurements are dependent.

b: A paired t-test is most appropriate because the measurements were taken from the same subjects at different times, before and after treatment, so the measurements are independent of each other.

c: An independent samples t-test is most appropriate because the measurements were taken from the same subjects at different times, before and after treatment, so the measurements are independent of each other.

d: An independent samples t-test is most appropriate because the same subjects were measured twice, first without treatment and then after treatment, so the measurements are dependent.

2: Suppose you are conducting a hypothesis test using the type of t-test you identified for the study in Question 1. You wish to determine if there is a difference in the mean calcium determinations. What is the null and alternate hypothesis for your hypothesis test?

A: Null: Difference in mean calcium determinations = 0.

Alternate: Difference in mean calcium determinations 0.

B: Null: Difference in mean calcium determinations = 0.

Alternate: Difference in mean calcium determinations > 0.

C: Null: Difference in mean calcium determinations = 0.

Alternate: Difference in mean calcium determinations < 0.

D: Null: Difference in mean calcium determinations 0.

Alternate: Difference in mean calcium determinations = 0.

3: Assume the pvalue is 0.02, what can you conclude about the differences in mean calcium determinations? Assume a significance level of = 0.05.

a:The p-value is less than the significance level so the results are statistically significant and we can conclude that there is a difference in mean calcium determinations.

b: The p-value is less than the significance level so there isn't enough evidence to conclude that there is a difference in mean calcium determinations.

c: The p-value is greater than the significance level so the results are statistically significant and we can conclude that there is a difference in mean calcium determinations.

d: The p-value is greater than the significance level so there isn't enough evidence to conclude that there is a difference in mean calcium determinations.