[Stata Program]
 
use http://www.gseis.ucla.edu/courses/data/immersion
  
generate schdum1 = (school==12)
generate schdum2 = (school==14)
generate inter = prelang*pgm
corr reading pgm sex prelang premath absent preschl books parlang momed daded
regress reading schdum1 schdum2 pgm prelang 
test schdum1 schdum2
regress reading pgm
regress reading prelang pgm
regress reading prelang pgm inter
tabulate pgm, summ (reading)
tabulate pgm, summ (prelang)
  
[Stata Program]
  
use http://www.gseis.ucla.edu/courses/data/immersion
  
generate schdum1 = (school==12)
generate schdum2 = (school==14)
generate inter = prelang*pgm
   
corr reading pgm sex prelang premath absent preschl books parlang momed daded
(obs=143)
  
             |  reading      pgm      sex  prelang  premath   absent  preschl    books  parlang
-------------+---------------------------------------------------------------------------------
     reading |   1.0000
         pgm |   0.2209   1.0000
         sex |  -0.0068   0.2069   1.0000
     prelang |   0.2098   0.0671   0.1936   1.0000
     premath |   0.1058   0.1348   0.0502   0.4062   1.0000
      absent |  -0.0273   0.0428  -0.0162  -0.0941  -0.0468   1.0000
     preschl |  -0.0856   0.0865  -0.0550  -0.1838  -0.0271   0.0941   1.0000
       books |   0.1073  -0.1610   0.0457   0.1108   0.0338   0.0053  -0.3068   1.0000
     parlang |   0.0451  -0.0172   0.0764   0.1127   0.0368   0.1565  -0.2080   0.1385   1.0000
       momed |  -0.0073   0.0625   0.0566   0.0287   0.0776   0.0734  -0.2404   0.3538   0.0826
       daded |  -0.0140  -0.1150   0.0521   0.1628   0.2078  -0.0600  -0.3993   0.4351   0.1872
 
             |    momed    daded
-------------+------------------
       momed |   1.0000
       daded |   0.5009   1.0000
 
regress reading schdum1 schdum2 pgm prelang 
 
      Source |       SS       df       MS              Number of obs =     143
-------------+------------------------------           F(  4,   138) =    4.18
       Model |  12607.0394     4  3151.75985           Prob > F      =  0.0032
    Residual |  104082.205   138  754.218879           R-squared     =  0.1080
-------------+------------------------------           Adj R-squared =  0.0822
       Total |  116689.245   142  821.755245           Root MSE      =  27.463

------------------------------------------------------------------------------
     reading |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
     schdum1 |  -5.901005     6.4485    -0.92   0.362    -18.65165    6.849636
     schdum2 |  -12.23476   6.879354    -1.78   0.078    -25.83733    1.367808
         pgm |   6.752536   2.675891     2.52   0.013     1.461487    12.04359
     prelang |   .2338472   .0924057     2.53   0.013     .0511332    .4165612
       _cons |   178.4792   15.74787    11.33   0.000     147.3409    209.6176
------------------------------------------------------------------------------
 
test schdum1 schdum2
 
 ( 1)  schdum1 = 0.0
 ( 2)  schdum2 = 0.0

       F(  2,   138) =    1.63
            Prob > F =    0.1996
             
regress reading pgm
 
      Source |       SS       df       MS              Number of obs =     143
-------------+------------------------------           F(  1,   141) =    7.23
       Model |  5693.25112     1  5693.25112           Prob > F      =  0.0080
    Residual |  110995.994   141  787.205629           R-squared     =  0.0488
-------------+------------------------------           Adj R-squared =  0.0420
       Total |  116689.245   142  821.755245           Root MSE      =  28.057

------------------------------------------------------------------------------
     reading |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
         pgm |   6.926803   2.575709     2.69   0.008     1.834803     12.0188
       _cons |    210.291   4.714075    44.61   0.000     200.9716    219.6104
------------------------------------------------------------------------------
 
regress reading prelang pgm
 
      Source |       SS       df       MS              Number of obs =     143
-------------+------------------------------           F(  2,   140) =    6.67
       Model |  10147.9507     2  5073.97533           Prob > F      =  0.0017
    Residual |  106541.294   140  761.009244           R-squared     =  0.0870
-------------+------------------------------           Adj R-squared =  0.0739
       Total |  116689.245   142  821.755245           Root MSE      =  27.586

------------------------------------------------------------------------------
     reading |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
     prelang |     .22072   .0912278     2.42   0.017     .0403576    .4010823
         pgm |   6.514449   2.538218     2.57   0.011     1.496256    11.53264
       _cons |   174.4681    15.5148    11.25   0.000     143.7945    205.1417
------------------------------------------------------------------------------
 
regress reading prelang pgm inter
 
      Source |       SS       df       MS              Number of obs =     143
-------------+------------------------------           F(  3,   139) =    4.61
       Model |  10560.8745     3   3520.2915           Prob > F      =  0.0042
    Residual |   106128.37   139  763.513455           R-squared     =  0.0905
-------------+------------------------------           Adj R-squared =  0.0709
       Total |  116689.245   142  821.755245           Root MSE      =  27.632

------------------------------------------------------------------------------
     reading |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-------------+----------------------------------------------------------------
     prelang |   .1030193   .1842973     0.56   0.577    -.2613692    .4674079
         pgm |  -5.597256   16.66451    -0.34   0.737    -38.54596    27.35145
       inter |   .0726358   .0987698     0.74   0.463    -.1226496    .2679212
       _cons |   193.9781   30.74598     6.31   0.000     133.1878    254.7683
------------------------------------------------------------------------------
 
tabulate pgm, summ (reading)
 
            |         Summary of reading
        pgm |        Mean   Std. Dev.       Freq.
------------+------------------------------------
          1 |   217.21782   28.549817         101
          3 |   231.07143   26.817716          42
------------+------------------------------------
      Total |   221.28671   28.666274         143
 
tabulate pgm, summ (prelang)
 
            |         Summary of prelang
        pgm |        Mean   Std. Dev.       Freq.
------------+------------------------------------
          1 |   164.16832   25.114565         101
          3 |   167.90476   26.302935          42
------------+------------------------------------
      Total |   165.26573   25.433412         143