Frequencies for first 10,000 rows of pctpovr variable in namcs2011 dataset :

     Recoded % of pop below poverty |
        level in patient's ZIP code |      Freq.     Percent        Cum.
------------------------------------+-----------------------------------
                       Missing data |        649        6.49        6.49
Quartile 1 (Less than 5.00 percent) |      2,288       22.88       29.37
     Quartile 2 (5.00-9.99 percent) |      2,910       29.10       58.47
   Quartile 3 (10.00-19.99 percent) |      2,996       29.96       88.43
 Quartile 4 (20.00 percent or more) |      1,157       11.57      100.00
------------------------------------+-----------------------------------
                              Total |     10,000      100.00

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