Frequencies for first 10,000 rows of vdatefl variable in nhamcsopd1996 dataset :

        was |
  patient's |
 visit date |
   imputed? |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,999       99.99       99.99
          1 |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 28 Mar 2016