Summary statistics for stch1990 dataset :

by Jean Roth , jroth@nber.org , 17 Oct 2016

    Variable |        Obs        Mean    Std. Dev.       Min        Max
-------------+---------------------------------------------------------
    agegroup |    954,864           9    5.477228          0         18
     racesex |    954,864         4.5    2.291289          1          8
      ethnic |    954,864         1.5    .5000003          1          2
         pop |    954,864    261.4224    1943.542          0     212760
        year |    954,864        1990           0       1990       1990
-------------+---------------------------------------------------------
       state |          0
      county |          0

by Jean Roth , jroth@nber.org , 17 Oct 2016