Frequencies for first 10,000 rows of paydk variable in nhamcsopd2009 dataset :

   expected |
  source of |
   payment: |
    unknown |      Freq.     Percent        Cum.
------------+-----------------------------------
         no |      9,660       96.60       96.60
        yes |        340        3.40      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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