options ls = 80 nodate;
libname fu '../../sdata';
data work;
	set fu.kidney;
/********************************************************************
** PROC LIFEREG does contain CLASS statement. Interaction terms    **
** involving CLASS variables, allowed in the GLM procedure, are    ** 
** not available in PROC LIFEREG                                   **
********************************************************************/
	if age = 2 then A2 = 1; else A2 = 0;
	if age = 3 then A3 = 1; else A3 = 0;
	A2N=A2*neph;
	A3N=A3*neph;
proc lifereg;
        model survt*censor(0)= / covb dist=weibull;
proc lifereg;
        model survt*censor(0)= A2 A3 / covb dist=weibull;
proc lifereg;
        model survt*censor(0)= neph / covb dist=weibull;
proc lifereg;
        model survt*censor(0)= neph A2 A3 / covb dist=weibull;
proc lifereg;
        model survt*censor(0)= A2 A3 neph A2N A3N / covb dist=weibull;
run;