Frequencies for first 10,000 rows of dechal variable in drug2008q1 dataset :

Dechallenge |
      code, |
 indicating |
if reaction |
abated when |
       drug |
therapy was |
    stopped |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,818       98.18       98.18
          D |         78        0.78       98.96
          N |         21        0.21       99.17
          U |         14        0.14       99.31
          Y |         69        0.69      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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