Frequencies for first 10,000 rows of urf_preterm variable in linkpe2009psden dataset :

   Previous |
 Preterm or |
  Small for |
Gestation U |
(f_urf_pret |
    erm rep |
      flag) |      Freq.     Percent        Cum.
------------+-----------------------------------
          . |     10,000      100.00      100.00
------------+-----------------------------------
      Total |     10,000      100.00

by Jean Roth , jroth@nber.org , 22 Dec 2015