Polychlorinated biphenyls (PCBs), industrial pollutants, are known to be carcinogens and a great danger to natural ecosystems. As a result of several studies, PCB production was banned in the United States in 1979 and by the Stockholm Convention on Persistent Organic Pollutants in 2001: One study, published in 1972 by R. Risebrough, is titled “Effects of Environmental Pollutants Upon Animals Other Than Man”. In that study, 50 Anacapa pelican eggs were collected and measured for their shell thickness, in millimetres (mm), and concentration of PCBs, in parts per million (ppm).
a) Obtain a scatterplot for the data.
b) Decide whether finding a regressimz line for the data is reasonable. If so, then also do parts (c)-(f).
c) Determine and interpret the regression equation for the data.
d) Identify potential outliers and influential observations.
e) In case a potential outlier is present, remove it and discuss the effect.
f) In case a potential influential observation is present, remove it and discuss the effect.