Frequencies for first 10,000 rows of spec variable in namcs2003 dataset :

  physician |
  specialty |      Freq.     Percent        Cum.
------------+-----------------------------------
         AI |         60        0.60        0.60
        CCP |         18        0.18        0.78
         CD |        548        5.48        6.26
        CHN |         71        0.71        6.97
        CHP |        136        1.36        8.33
         CN |         41        0.41        8.74
        CRS |         11        0.11        8.85
          D |        634        6.34       15.19
         EM |         49        0.49       15.68
        END |         30        0.30       15.98
         FP |      1,439       14.39       30.37
        FPS |         15        0.15       30.52
        FSM |         10        0.10       30.62
         GE |        142        1.42       32.04
         GP |        203        2.03       34.07
         GS |        412        4.12       38.19
        GYN |         89        0.89       39.08
         HS |         29        0.29       39.37
         IM |        641        6.41       45.78
        MFM |         25        0.25       46.03
          N |        607        6.07       52.10
        NEP |         81        0.81       52.91
        OBG |        443        4.43       57.34
         ON |         43        0.43       57.77
        OPH |        611        6.11       63.88
        ORS |        554        5.54       69.42
         OS |         28        0.28       69.70
        OSM |         18        0.18       69.88
        OTO |        928        9.28       79.16
          P |        398        3.98       83.14
        PCC |         44        0.44       83.58
         PD |        713        7.13       90.71
        PDS |         33        0.33       91.04
         PM |         90        0.90       91.94
         PS |         72        0.72       92.66
        PUD |         19        0.19       92.85
        PYA |         36        0.36       93.21
        REN |         18        0.18       93.39
        RHU |         27        0.27       93.66
         TS |         25        0.25       93.91
          U |        508        5.08       98.99
         UP |          9        0.09       99.08
         VS |         92        0.92      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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