Frequencies for first 10,000 rows of hincomer variable in nhamcsopd2010 dataset :

  median household income in |
               patient's zip |      Freq.     Percent        Cum.
-----------------------------+-----------------------------------
                missing data |        401        4.01        4.01
  quartile 1 (below $32,793) |      2,799       27.99       32.00
quartile 2 ($32,794-$40,626) |      2,813       28.13       60.13
quartile 3 ($40,627-$52,387) |      2,403       24.03       84.16
quartile 4 ($52,388 or more) |      1,584       15.84      100.00
-----------------------------+-----------------------------------
                       Total |     10,000      100.00

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