Frequencies for first 10,000 rows of senbefor variable in nhamcsopd1994 dataset :

has patient |
  been seen |
    in this |
     clinic |
    before? |      Freq.     Percent        Cum.
------------+-----------------------------------
        Yes |      7,927       79.27       79.27
         No |      2,073       20.73      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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