5 Refer to Example 11.2 on Y = mental impairment. X = life events. and X = SES.

a) Show that forward selection with X. X. X = XX. XX. and X, = X and the a=.10 level for inchision selects only X1 and X2 for the model.

b) Use backward climination. What is the final model? Interpret

c) Use the C, index to describe the fit provided by each model considered in the process (b). in