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

   psa test |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,972       99.72       99.72
          1 |         28        0.28      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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