Frequencies for first 10,000 rows of rx6v1c2 variable in nhamcsopd2006 dataset :

   for rx6, level 1 of multum |
             drug category #2 |      Freq.     Percent        Cum.
------------------------------+-----------------------------------
              Anti-infectives |          7        0.07        0.07
        Cardiovascular agents |         17        0.17        0.24
Central nervous system agents |         22        0.22        0.46
        Coagulation modifiers |         49        0.49        0.95
                     Hormones |          5        0.05        1.00
         Miscellaneous agents |          8        0.08        1.08
         Nutritional products |          5        0.05        1.13
           Respiratory agents |         11        0.11        1.24
               Topical agents |          4        0.04        1.28
     Psychotherapeutic agents |          4        0.04        1.32
             Metabolic agents |          5        0.05        1.37
                            . |      9,863       98.63      100.00
------------------------------+-----------------------------------
                        Total |     10,000      100.00

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