Frequencies for first 10,000 rows of rechal variable in drug2017q1 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,542       85.42       85.42
          N |        171        1.71       87.13
          U |      1,242       12.42       99.55
          Y |         45        0.45      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 18 Sep 2017