/* SAS code for the rat data */

/* Variables
    Litter number: 
       even litter numbers are males, 
       odd litter numbers are female
   Exposure: 0=no, 1=yes
   Time: Follow-up time
   Status: 0-tumor, 1-censored 
*/


data rats;
    infile 'c:\documents and settings\kkoehler.IASTATE\my documents\courses\st565\sas\therneau\rats.dat';
    input litter rx time status;
run;

%include 'c:\documents and settings\kkoehler.IASTATE\my documents\courses\st565\sas\therneau\phlev.sas';

%phlev(data=rats, time=time, event=status,
       xvars = rx, id=litter, outlev=phlev,
       outvar= phvar );


proc phreg data=rats covm covs;
 model time*status(0)= rx /ties=efron;
run;