Frequencies for first 10,000 rows of dechal variable in drug2008q3 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,788       97.88       97.88
          D |        115        1.15       99.03
          N |          5        0.05       99.08
          U |         23        0.23       99.31
          Y |         69        0.69      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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