In Problem 2.6, you used four simple regression analyses to try to draw conclusions about the factors related to urinary calcium loss UCa in patients receiving parenteral nutrition. (The data are in Table D-5, Appendix D.) A. Repeat that analysis using multiple regression to consider the simultaneous effects of all four variables, DCa, Dp, UNa, and Gfr. Which variables seem to be important determinants of UCa? B.
Compare this multivariate result to the result of the four univariate correlation analyses done in Problem 2.6. C. Why are there differences, and which approach is preferable?