Reference : Applied Linear Statistical Models Fifth Edition Michael H. Kutner book problem no. 8.39. Using the data set APPENC02 data link here (cnachtsheim-text.csom.umn.edu/Kutner/Appendix C Data Sets/APPENC02.txt), also called CDI, the number of physicians (Y ) is to be regressed against total population (X1), total personal income (X2), and geographic region (X3, X4, X5). "The variables names are attached below"