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

     survey |
 identifier |
(constant=2 |
for nhamcs) |      Freq.     Percent        Cum.
------------+-----------------------------------
          2 |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

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