Frequencies for first 10,000 rows of dechal variable in drug2006q4 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,174       91.74       91.74
          D |        365        3.65       95.39
          N |         92        0.92       96.31
          U |        162        1.62       97.93
          Y |        207        2.07      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Dec 2015