Frequencies for first 10,000 rows of pctpovr variable in nhamcsed2007 dataset :

 percent pop below poverty level in |
                 patient's zip code |      Freq.     Percent        Cum.
------------------------------------+-----------------------------------
                       missing data |        657        6.57        6.57
quartile 1 (less than 5.00 percent) |      1,453       14.53       21.10
     quartile 2 (5.00-9.99 percent) |      2,419       24.19       45.29
   quartile 3 (10.00-19.99 percent) |      3,238       32.38       77.67
 quartile 4 (20.00 percent or more) |      2,233       22.33      100.00
------------------------------------+-----------------------------------
                              Total |     10,000      100.00

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