Consider the data given here. Pair

Med. 6.27 Suppose you are a participant in a project to study the effectiveness of a new treatment for high cholesterol. The new treatment will be compared to a current treatment by recording the change in cholesterol readings over a 10-week treatment period. The effectiveness of the treatment may depend on the participant’s age, body fat percentage, diet, and general health. The study will involve at most 30 participants because of cost considerations. a. Describe how you would conduct the study using independent samples. b. Describe how you would conduct the study using paired samples.

c. How would you decide which method, paired or independent samples, would be more

efficient in evaluating the change in cholesterol readings? Med. 6.28 The paper “Effect of long-term blood pressure control on salt sensitivity” [Journal of Medicine 1997 28:147–156] describes a study evaluating salt sensitivity SENS after a period of antihypertensive treatment. Ten hypertensive patients diastolic blood pressure between 90 and 115 mmHg were studied after at least 18 months on antihypertensive treatment. SENS readings, which were obtained before and after the patients were placed on an antihypertensive treatment, are given here: Patient 1 2 3 4 5 6 7 8 9 10 Before treatment 22.86 7.74 15.49 9.97 1.44 9.39 11.40 1.86 ⫺ 6.71 6.42 After treatment 6.11 ⫺ 4.02 8.04 3.29 ⫺ 0.77 6.99 10.19 2.09 11.40 10.70

a. Is there significant evidence that the mean SENS value decreased after the patient

received antihypertensive treatment? b. Estimate the size of the change in the mean SENS value. c. Do the conditions required for using the t procedures appear to be valid for these data? Justify your answer. Edu. 6.29 A study was designed to measure the effect of home environment on academic achieve- ment of 12-year-old students. Because genetic differences may also contribute to academic achievement, the researcher wanted to control for this factor. Thirty sets of identical twins were identified who had been adopted prior to their first birthday, with one twin placed in a home in which academics were emphasized Academic and the other twin placed in a home in which academics were not emphasized Nonacademic. The final grades based on 100 points for the 60 students are given here: Set of Set of Twins Academic Nonacademic Twins Academic Nonacademic 1 78 71 16 90 88 2 75 70 17 89 80 3 68 66 18 73 65 4 92 85 19 61 60 5 55 60 20 76 74 6 74 72 21 81 76 7 65 57 22 89 78 8 80 75 23 82 78 9 98 92 24 70 62 10 52 56 25 68 73 11 67 63 26 74 73 12 55 52 27 85 75 13 49 48 28 97 88 14 66 67 29 95 94 15 75 70 30 78 75

a. Use the following computer output to evaluate whether there is a difference in the

mean final grade between the students in an academically oriented home environment and those in a nonacademically oriented home environment.

b. Estimate the size of the difference in the mean final grades of the students in academic

and nonacademic home environments.