Frequencies for first 10,000 rows of hincomer variable in nhamcsopd2008 dataset :

  median household income in |
          patient's zip code |      Freq.     Percent        Cum.
-----------------------------+-----------------------------------
                missing data |        471        4.71        4.71
  quartile 1 (below $32,793) |      3,367       33.67       38.38
quartile 2 ($32,794-$40,626) |      1,952       19.52       57.90
quartile 3 ($40,627-$52,387) |      1,944       19.44       77.34
quartile 4 ($52,388 or more) |      2,266       22.66      100.00
-----------------------------+-----------------------------------
                       Total |     10,000      100.00

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