The accompanying data on x 5 head circumference z score (a comparison score with peers o...

The accompanying data on x 5 head circumference z score (a comparison score with peers of the same age—a positive score suggests a larger size than for peers) at age 6 to 14 months and y 5 volume of cerebral grey matter (in ml) at age 2 to 5 years were read from a graph in the article described in the chapter introduction (Journal of the American Medical Association [2003]).

a. Construct a scatterplot for these data.

b. What is the value of the correlation coefficient?

c. Find the equation of the least-squares line.

d. Predict the volume of cerebral grey matter at age 2 to 5 years for a child whose head circumference z score at age 12 months was 1.8.

e. Explain why it would not be a good idea to use the least-squares line to predict the volume of grey matter for a child whose head circumference z score was 3.0.