Frequencies for first 10,000 rows of ngtube variable in nhamcsed1993 dataset :

         ng |
tube/gastri |
   c lavage |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,923       99.23       99.23
          1 |         77        0.77      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016