Frequencies for first 10,000 rows of paydk variable in nhamcsopd2006 dataset :

   expected |
  source of |
   payment: |
    unknown |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,736       97.36       97.36
          1 |        264        2.64      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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