title "Exercise 1 in Chapter 1 of Hosmer and Lemeshow";

/* Input data and create a dummy observation to get predicted
values for AGE=60 for one part of the exercise. */ 

data ICU;
  infile "c:\friday\logistic\icu.dat";
  input ID STA AGE SEX RACE SER CAN CRN INF CPR
        SYS HRA PRE TYP FRA PO2 PH PCO BIC CRE LOC;
  if _n_ = 1 then do;
    statmp = STA;
    agetmp = AGE;
    STA = .;
    AGE = 60;
   output;
    STA = statmp;
    AGE = agetmp;
  end;
  output;
  drop statmp agetmp;

/* SAS models PR(STA=0) unless the "DESCENDING" option is specified */

proc logistic data=ICU;
  model STA (descending) = AGE /covb clparm=wald link=logit;
  output 
    out=ICUOUT p=PRED lower=LPRED upper=UPRED xbeta=LOGEST sdtxbeta=LOGESTSE 
    /alpha=0.05;

proc print data=ICUOUT (OBS=1);
  var AGE PRED LPRED UPRED LOGEST LOGESTSE;

proc plot data=ICUOUT;
  plot pred*age lpred*age upred*age /overlay;
run;  

proc catmod data=ICU;
  direct AGE;
  model STA = AGE /covb clparm;
run;