Frequencies for first 10,000 rows of pctpovr variable in nhamcsopd2007 dataset :

   percent poverty in patient's zip |      Freq.     Percent        Cum.
------------------------------------+-----------------------------------
                       missing data |        367        3.67        3.67
quartile 1 (less than 5.00 percent) |      1,343       13.43       17.10
     quartile 2 (5.00-9.99 percent) |      2,434       24.34       41.44
   quartile 3 (10.00-19.99 percent) |      3,177       31.77       73.21
 quartile 4 (20.00 percent or more) |      2,679       26.79      100.00
------------------------------------+-----------------------------------
                              Total |     10,000      100.00

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