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

  percent pop w/bachelor's degree or |
        higher in patient's zip code |      Freq.     Percent        Cum.
-------------------------------------+-----------------------------------
                        missing data |        367        3.67        3.67
quartile 1 (less than 12.84 percent) |      3,180       31.80       35.47
    quartile 2 (12.84-19.66 percent) |      2,339       23.39       58.86
    quartile 3 (19.67-31.68 percent) |      2,130       21.30       80.16
  quartile 4 (31.69 percent or more) |      1,984       19.84      100.00
-------------------------------------+-----------------------------------
                               Total |     10,000      100.00

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