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       log:  d:\bill\fall2008\econ30331\educ_earn.log
  log type:  text
 opened on:  10 Sep 2008, 10:26:27

. 
. * the data set is big so increase memory
. set memory 2m

Current memory allocation

                    current                                 memory usage
    settable          value     description                 (1M = 1024k)
    --------------------------------------------------------------------
    set maxvar         5000     max. variables allowed           1.909M
    set memory            2M    max. data space                  2.000M
    set matsize         400     max. RHS vars in models          1.254M
                                                            -----------
                                                                 5.163M

. 
. * read in data
. * this is the data set from the intro to
. * stata handout
. use cps87

. 
. * construct ln weekly earnings
. gen ln_weekly_earn=ln(weekly_earn)

. 
. * get descriptive information
. sum weekly_earn ln_weekly_earn years_educ 

    Variable |       Obs        Mean    Std. Dev.       Min        Max
-------------+--------------------------------------------------------
 weekly_earn |     19906     488.264    236.4713         60        999
ln_weekly_~n |     19906    6.067307     .513047   4.094345   6.906755
  years_educ |     19906    13.16126    2.795234          0         18

. 
. * run simple regression
. reg ln_weekly_earn years_educ

      Source |       SS       df       MS              Number of obs =   19906
-------------+------------------------------           F(  1, 19904) = 3877.62
       Model |   854.28055     1   854.28055           Prob > F      =  0.0000
    Residual |  4385.05814 19904  .220310397           R-squared     =  0.1631
-------------+------------------------------           Adj R-squared =  0.1630
       Total |  5239.33869 19905  .263217216           Root MSE      =  .46937

------------------------------------------------------------------------------
ln_weekly_~n |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
  years_educ |   .0741141   .0011902    62.27   0.000     .0717813     .076447
       _cons |   5.091872   .0160138   317.97   0.000     5.060484    5.123261
------------------------------------------------------------------------------

. 
. * generate new variable for age squared
. gen age2=age*age

. 
. * run regression controlling for
. * educ and quadratic in age
. reg ln_weekly_earn years_educ age age2

      Source |       SS       df       MS              Number of obs =   19906
-------------+------------------------------           F(  3, 19902) = 2644.18
       Model |  1493.15489     3  497.718296           Prob > F      =  0.0000
    Residual |   3746.1838 19902  .188231524           R-squared     =  0.2850
-------------+------------------------------           Adj R-squared =  0.2849
       Total |  5239.33869 19905  .263217216           Root MSE      =  .43386

------------------------------------------------------------------------------
ln_weekly_~n |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
  years_educ |   .0719499   .0011135    64.62   0.000     .0697674    .0741324
         age |   .0712533   .0020266    35.16   0.000      .067281    .0752256
        age2 |  -.0007069   .0000248   -28.51   0.000    -.0007555   -.0006583
       _cons |   3.522066   .0397997    88.49   0.000     3.444055    3.600077
------------------------------------------------------------------------------

. 
. log close
       log:  d:\bill\fall2008\econ30331\educ_earn.log
  log type:  text
 closed on:  10 Sep 2008, 10:26:27
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