Abstract: Does increasing calcium intake reduce blood pressure? Observational studies suggest that there is a link, and that it is strongest in African-American men. Twenty-one African-American men participated in an experiment to test this hypothesis. Ten of the men took a calcium supplement for 12 weeks while the remaining 11 men recieved a placebo. Researchers measured the blood pressure of each subject before and after the 12-week period. The experiment was double-blind.
Reference: Moore, David S., and George P. McCabe (1989). Introduction
to the Practice of Statistics. Original source: Lyle, Roseann M., et al.,
"Blood pressure and metabolic effects of calcium supplementation in
normotensive white and black men," JAMA, 257(1987), pp. 1772-1776,
Did the calcium supplement reduce the diastolic blood pressure in the treatment
group after the 12 week experimental period? Use alpha < 0.05 to answer
this question.
A. Write the null hypothesis for the comparison.
B. Write the alternative hypothesis for the comparison.
C. Perform the appropriate statistical analysis in Excel and print your results from the spreadsheet.
D. What do you conclude? Justify your answer.
E. Create a column graph for the two groups (both pre and post treatment) and indicate the standard error bars on each column.
To download the datafile for the homework question: 317HW7a.xls. To download this file in Internet Explorer, right-click on the link, left-click on Save Target As ...., left-click on Save, the file will download. When the download is completed, left-click on Close. To download the file in Netscape Navigator, left-click on the link, check the Save it to Disk button, left-click OK, left-click Save, the file will download. Open the file 317HW7a.xls in Microsoft Excel. To do this, start Excel, left-click on File > Open, locate and single left-click the file in the Open dialog box, and left-click Open.
Abstract: Is it harder to maintain your balance while you are concentrating? Nine elderly (6 men and 3 women) and eight young men were subjects in this experiment. Each subject stood barefoot on a "force platform" and was asked to maintain a stable upright position and to react as quickly as possible to an unpredictable noise by pressing a hand held button. The noise came randomly and the subject concentrated on reacting as quickly as possible. The platform automatically measured how much each subject swayed in millimeters in both the forward/backward and the side-to-side directions.
Reference: Teasdale, Bard, LaRue, and Fleury. (1993). Experimental
Aging Research
Does age affect forward/backward sway? Use alpha < 0.05 to answer this
question.
A. Write the null hypothesis for the comparison.
B. Perform the appropriate statistical analysis in Excel and print your results from the spreadsheet.
C. What do you conclude? Justify your answer.
Does age affect side-to-side sway? Use alpha < 0.05 to answer this question.
D. Write the null hypothesis for the comparison.
E. Perform the appropriate statistical analysis in Excel and print your results from the spreadsheet.
F. What do you conclude? Justify your answer.
To download the datafile for the homework question: 317HW7b.xls. To download this file in Internet Explorer, right-click on the link, left-click on Save Target As ...., left-click on Save, the file will download. When the download is completed, left-click on Close. To download the file in Netscape Navigator, left-click on the link, check the Save it to Disk button, left-click OK, left-click Save, the file will download. Open the file 317HW7b.xls in Microsoft Excel. To do this, start Excel, left-click on File > Open, locate and single left-click the file in the Open dialog box, and left-click Open.