Frequencies for first 10,000 rows of pttinr variable in nhamcsed2009 dataset :

prothrombin |
   time/inr |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,223       92.23       92.23
          1 |        777        7.77      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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