The paper "Accelerated Telomere Shortening in Response to Life Stress" (Proceedings of the National Academy of Sciences [2004]: 17312-17315) described a study that examined whether stress accelerates aging at a cellular level. The accompanying data on a measure of perceived stress (x) and telomere length (y) were read from a scatterplot that appeared in the paper. Telomere length is a measure of cell longevity
a. Compute the equation of the least-squares line.
b. What is the value of r2 ?
c. Does the linear relationship between perceived stress and telomere length account for a large or small proportion of the variability in telomere length? Justify your answer.