8. Use the cornputer output from Problem 12 in (11apter it :¦11(1 the output given here to answer the following questions. a. State model that relates change in refraction (Y) to baseline refraction...

8. Use the cornputer output from Problem 12 in (11apter it :¦11(1 the output given here to answer the following questions. a. State model that relates change in refraction (Y) to baseline refraction (X,), baseline curvature (X2). and the interaction of X, and X2. Is the partial F test for the interaction significant? b. Is it appropriate to assess confounding. given your answer to part (a)? Explain. c. If your answer to part (b) is yes, does X, confound the relationship between Y and X,? d. If your answer to part (b) is ycs, does Xi confound the relationship between Y and X2? e. In light of your answers to parts (a) through (d), and on considerations of precision. which predictor(s) should be included in the model?
EditedSAS Output (PROC UM) for Prob.,: 8
Y Red,xxed on X, X2, and X1X2
-0.52636869 -0.06778472
"1'2'58 0.79 0.37006537 -1.42 0.07750534 -0.87
"0'.111919 0.4339 0.3681631