Frequencies for first 10,000 rows of pttinr variable in nhamcsed2012 dataset :

Prothrombin |
   time/INR |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,145       91.45       91.45
        Yes |        855        8.55      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 7 Nov 2016