Frequencies for first 10,000 rows of rx4v1c2 variable in nhamcsopd2006 dataset :

   for rx4, level 1 of multum |
             drug category #2 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
              Anti-infectives |         16        0.16        0.16
        Cardiovascular agents |         14        0.14        0.30
Central nervous system agents |         68        0.68        0.98
        Coagulation modifiers |         56        0.56        1.54
      Gastrointestinal agents |          2        0.02        1.56
                     Hormones |         19        0.19        1.75
         Miscellaneous agents |         26        0.26        2.01
         Nutritional products |          9        0.09        2.10
           Respiratory agents |         19        0.19        2.29
               Topical agents |          8        0.08        2.37
     Psychotherapeutic agents |          5        0.05        2.42
             Metabolic agents |          3        0.03        2.45
                            . |      9,755       97.55      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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