Frequencies for first 10,000 rows of rechal variable in drug2005q4 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,707       87.07       87.07
          D |      1,062       10.62       97.69
          N |         20        0.20       97.89
          U |        192        1.92       99.81
          Y |         19        0.19      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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