data mel; filename melfile url "http://publicifsv.sund.ku.dk/~pka/epidata/melanom-surv.txt"; infile melfile firstobs=2; input id dc days ulc thick sex age; run; /* age and thick are rescaled */ data mel; set mel; age=age/10; thick=thick/100; run; /* 1.: slide 17 */ proc phreg data=mel; class sex (ref="1") ulc (ref="2"); model days*dc(2)=sex ulc thick age/rl; run; /* 2.: proportionality for ulc */ proc phreg data=mel; class sex (ref="1") ulc; model days*dc(2)=sex ulc thick age ulctime/rl; ulctime=(ulc-1)*log(days); run; /* 3.: linear splines for thick */ data mel; set mel; thick2=(thick-2)*(thick>2); thick5=(thick-5)*(thick>5); run; proc phreg data=mel; class sex (ref="1") ulc (ref="2"); model days*dc(2)=sex ulc thick age thick2 thick5/rl; Linarity_thick: test thick2, thick5; run; /* 4.: interaction sex*thick */ proc phreg data=mel; class sex (ref="1") ulc (ref="2"); model days*dc(2)=sex ulc thick age sex*thick/rl; run;