Polychlorinated biphenyls (PCBs), industrial pollutants, are a great danger to natural ecosystems. In a study by R. W. Risebrough titled “Effects of Environmental Pollutants Upon Animals Other Than Man” (Proceedings of the 6th Berkeley Symposium on Mathematics and Statistics, VI, University of California Press, pp. 443–463), 60 Anacapa pelican eggs were collected and measured for their shell thickness, in millimeters (mm), and concentration of PCBs, in parts per million (ppm). The data are presented on the Weiss Stats CD.
a. Obtain and interpret the standard error of the estimate.
b. Obtain a residual plot and a normal probability plot of the residuals.
c. Decide whether you can reasonably consider Assumptions 1–3 for regression inferences met by the two variables under consideration.