Refer to the International Journal of Obesity (Jan. 2007) study of the physical activity of obese young adults, presented in Exercise 6.37 (p. 303). For two groups of young adults-13 obese and 15 of normal weight-researchers recorded the total number of registered movements (counts) of each young adult over a period of time. Baseline physical activity was then computed as the number of counts per minute (cpm). Four years later, physical activity measurements were taken again-called physical activity at follow-up.
a. For the 13 obese young adults, the researchers reported a correlation of r = .50 between baseline and follow-up physical activity, with an associated p-value of .07. Give a practical interpretation of this correlation coefficient and p-value.
b. Refer to part a. Construct a scatterplot of the 13 data points that would yield a value of r = .50.
c. For the 15 young adults of normal weight, the researchers reported a correlation of r = -.12 between baseline and follow-up physical activity, with an associated p-value of .66. Give a practical interpretation of this correlation coefficient and p-value.
d. Refer to part c. Construct a scatterplot of the 15 data points that would yield a value of r = -12.