Frequencies for first 10,000 rows of rechal variable in drug2004q1 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      8,110       81.10       81.10
          D |      1,582       15.82       96.92
          N |         45        0.45       97.37
          U |        206        2.06       99.43
          Y |         57        0.57      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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