Frequencies for first 10,000 rows of senbefor variable in nhamcsopd1993 dataset :

has patient |
  been seen |
    in this |
     clinic |
    before? |      Freq.     Percent        Cum.
------------+-----------------------------------
        Yes |      7,681       76.81       76.81
         No |      2,319       23.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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