Frequencies for first 10,000 rows of pttinr variable in nhamcsed2007 dataset :

prothrombin |
   time/inr |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,088       90.88       90.88
        yes |        912        9.12      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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