Frequencies for first 10,000 rows of refothph variable in nhamcsopd1992 dataset :

   Refer to |
    another |
  physician |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,212       92.12       92.12
          1 |        788        7.88      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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