Frequencies for first 10,000 rows of spec variable in namcs2000 dataset :

  physician |
  specialty |      Freq.     Percent        Cum.
------------+-----------------------------------
         CD |         15        0.15        0.15
        CRS |         27        0.27        0.42
          D |         67        0.67        1.09
         EM |         66        0.66        1.75
        END |         31        0.31        2.06
         FP |      3,124       31.24       33.30
        FPG |         14        0.14       33.44
         GE |         11        0.11       33.55
         GP |        206        2.06       35.61
        GPM |         17        0.17       35.78
         GS |      1,287       12.87       48.65
         IM |      2,272       22.72       71.37
        MPD |         61        0.61       71.98
        NEP |         34        0.34       72.32
        NPM |         55        0.55       72.87
        OBG |        195        1.95       74.82
        ORS |         94        0.94       75.76
          P |         27        0.27       76.03
         PD |      2,244       22.44       98.47
        PDA |          7        0.07       98.54
        PDC |         24        0.24       98.78
        RHU |         55        0.55       99.33
         SO |         15        0.15       99.48
          U |         23        0.23       99.71
         VS |         29        0.29      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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