11.47 Predicting the total amount of PCB. Use the four congeners PCB52, PCB118, PCB138, and PCB180 in a multiple regression to predict PCB.

  1. (a) Write the statistical model for this analysis. Include all assumptions.

  2. (b) Run the regression and summarize the results.

  3. (c) Examine the residuals. Do they appear to be approximately Normal? When you plot them versus each of the explanatory variables, are any patterns evident?