Frequencies for first 10,000 rows of pttinr variable in nhamcsed2013 dataset :

Prothrombin |
   time/INR |      Freq.     Percent        Cum.
------------+-----------------------------------
         No |      9,055       90.55       90.55
        Yes |        945        9.45      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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