Frequencies for first 10,000 rows of rechal variable in drug2005q1 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      7,539       75.39       75.39
          D |      1,748       17.48       92.87
          N |         33        0.33       93.20
          U |        634        6.34       99.54
          Y |         46        0.46      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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