Frequencies for first 10,000 rows of rechal variable in drug2007q4 dataset :

Rechallenge |
      code, |
 indicating |
if reaction |
   recurred |
  when drug |
    therapy |
  restarted |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,647       96.47       96.47
          D |        279        2.79       99.26
          N |          6        0.06       99.32
          U |         60        0.60       99.92
          Y |          8        0.08      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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