Frequencies for first 10,000 rows of refer variable in namcs1998 dataset :

    was pat |
referred by |
        oth |
  physician |
 for visit? |      Freq.     Percent        Cum.
------------+-----------------------------------
          1 |      1,133       11.33       11.33
          2 |      8,460       84.60       95.93
          3 |        336        3.36       99.29
          4 |         71        0.71      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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