Frequencies for first 10,000 rows of rx1v1c2 variable in nhamcsopd2006 dataset :

   for rx1, level 1 of multum |
             drug category #2 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
              Anti-infectives |        103        1.03        1.03
              Antineoplastics |          3        0.03        1.06
        Cardiovascular agents |         22        0.22        1.28
Central nervous system agents |         98        0.98        2.26
        Coagulation modifiers |         69        0.69        2.95
      Gastrointestinal agents |          2        0.02        2.97
                     Hormones |        106        1.06        4.03
         Miscellaneous agents |        136        1.36        5.39
         Nutritional products |         12        0.12        5.51
           Respiratory agents |         42        0.42        5.93
               Topical agents |         43        0.43        6.36
     Psychotherapeutic agents |          6        0.06        6.42
             Metabolic agents |         15        0.15        6.57
           Pharmaceutical aid |          1        0.01        6.58
                            . |      9,342       93.42      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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