Frequencies for first 10,000 rows of prov1590 variable in pos1993 dataset :

    patient |
   dialysis |
   training |
       code |      Freq.     Percent        Cum.
------------+-----------------------------------
            |      9,878       98.78       98.78
          A |        121        1.21       99.99
          B |          1        0.01      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 26 Jan 2016