Frequencies for first 10,000 rows of pregtest variable in nhamcsed2002 dataset :

  pregnancy |
       test |      Freq.     Percent        Cum.
------------+-----------------------------------
          0 |      9,623       96.23       96.23
          1 |        377        3.77      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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