Launched in 1973 the Bogalusa Heart Study is a National Inst

Launched in 1973, the Bogalusa Heart Study is a National Institutes of Health (NIH) prospective study of diet and cardiovascular disease risk. Among its many objectives was a comparison of Caucasians and African Americans. In one set of analyses, the average seated systolic blood pressure of the 1554 Caucasian girls was reported to 104.4 mmHg with a sample standard deviation of 9.0 mmHg; for the 927 African American girls the average seated systolic blood pressure was 104.7 mmHg with a sample standard deviation of 9.3 mmHg.

2a. State the appropriate formula to calculate a 95% confidence interval for the difference in mean blood pressure of the two ethnic groups from which the subjects were recruited. State any assumptions you need to use the formula.

2b. Using the formula you gave in question 2a, obtain the 95% confidence interval for the difference in mean blood pressure of the two ethnic groups from which the subjects were recruited. In 1 sentence, interpret the confidence interval you obtained in 2b.

Solution