Frequencies for first 10,000 rows of ewarno variable in nhamcsopd2008 dataset :

   if yes, are |
there warnings |
       of drug |
 interactions? |      Freq.     Percent        Cum.
---------------+-----------------------------------
         blank |        309        3.09        3.09
       unknown |        873        8.73       11.82
not applicable |      5,850       58.50       70.32
           yes |      2,299       22.99       93.31
            no |        669        6.69      100.00
---------------+-----------------------------------
         Total |     10,000      100.00

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