/* ---------------------------------------------------------------
 program: nickel-v92.sas
 input:   nickelc.dat
 does:    use counting process format for handling left truncation 
--------------------------------------------------------------- */;

OPTIONS PS=68 LS=120 PAGENO=1 NODATE NOCENTER ERRORS=3;

filename INF "H:\bios180\coursepack\SAS-unc-workshop-2008\nickelc.dat";
*******************************************************;
data A;
  infile INF;
  input id icd exposure birthday afe enterage exitage;

** create variables;
tl = enterage-afe;
if exitage gt 85 then truncage = 85;
                 else truncage = exitage;
tr = truncage-afe;
if icd=160 then delta = 1;
           else delta = 0;
yfe = birthday + afe;
logafe = log(afe-10);
yfe10 = (yfe-1915)/10;
yfe100 = (yfe-1915)**2 / 100;
logexp = log(exposure+1);

lable yfe ="Year of First Employment"
      tl  ="Entering time";
run;

proc phreg data=a;
  model (tl,tr)*delta(0)=logafe yfe10 yfe100 logexp;
run;