/* senic0.1.sas */
data  simple;
      missing X R; /* These are missing values for any numeric variable. */
      infile '/folders/myfolders/2453f15/senicdata.txt';
      input   id stay age infrisk culratio xratio nbeds medschl $
              region census nurses service;
      if medschl = '?' then medschl = ' ' ; /* Blank=missing for character vars */
proc freq;
      tables _all_;