Return to the data on liver transplant patients in Exercise 8.10 (in Table XXXXXXXXXXThe response variable of interest is TIME or some appropriate transform. You decide to categorize PROG into two...

Return to the data on liver transplant patients in Exercise 8.10 (in Table 8.31). The response variable of interest is TIME or some appropriate transform. You decide to categorize PROG into two categories above and below the median (a median split), and to do the same with the variable LIV. Your question is whether knowing LIV improves the predictability of TIME after controlling for PROG. Note: The four combinations of PROG category and LIV category will not be exactly balanced. Use appropriate software.