use https://stats.idre.ucla.edu/stat/stata/examples/methods_matter/chapter11/colombia_voucher, clear
Descriptive statistics for Table 11.1 on page 270.
sum finish8th use_fin_aid won_lottry base_age male
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
finish8th | 1171 .6814688 .4661058 0 1
use_fin_aid | 1171 .5815542 .4935148 0 1
won_lottry | 1171 .5055508 .5001828 0 1
base_age | 1171 12.00427 1.347038 7 17
male | 1171 .5046968 .5001916 0 1
sort won_lottry
by won_lottry: sum finish8th use_fin_aid won_lottry base_age male
-----------------------------------------------------------------------------------------
-> won_lottry = 0
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
finish8th | 579 .6252159 .4844857 0 1
use_fin_aid | 579 .2400691 .4274945 0 1
won_lottry | 579 0 0 0 0
base_age | 579 12.03627 1.351814 7 16
male | 579 .5043178 .5004137 0 1
-----------------------------------------------------------------------------------------
-> won_lottry = 1
Variable | Obs Mean Std. Dev. Min Max
-------------+--------------------------------------------------------
finish8th | 592 .7364865 .440911 0 1
use_fin_aid | 592 .9155405 .2783108 0 1
won_lottry | 592 1 0 1 1
base_age | 592 11.97297 1.342755 9 17
male | 592 .5050676 .5003971 0 1
Significance tests for Table 11.1 on page 270.
reg finish8th won_lottry
Source | SS df MS Number of obs = 1171
-------------+------------------------------ F( 1, 1169) = 16.91
Model | 3.62413371 1 3.62413371 Prob > F = 0.0000
Residual | 250.56374 1169 .214340239 R-squared = 0.0143
-------------+------------------------------ Adj R-squared = 0.0134
Total | 254.187874 1170 .217254593 Root MSE = .46297
------------------------------------------------------------------------------
finish8th | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
won_lottry | .1112706 .0270601 4.11 0.000 .0581787 .1643625
_cons | .6252159 .0192403 32.50 0.000 .5874664 .6629653
------------------------------------------------------------------------------
reg use_fin_aid won_lottry
Source | SS df MS Number of obs = 1171
-------------+------------------------------ F( 1, 1169) = 1031.16
Model | 133.554147 1 133.554147 Prob > F = 0.0000
Residual | 151.407424 1169 .129518755 R-squared = 0.4687
-------------+------------------------------ Adj R-squared = 0.4682
Total | 284.961571 1170 .243556899 Root MSE = .35989
------------------------------------------------------------------------------
use_fin_aid | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
won_lottry | .6754715 .0210351 32.11 0.000 .6342007 .7167422
_cons | .2400691 .0149564 16.05 0.000 .2107247 .2694135
------------------------------------------------------------------------------
reg base_age won_lottry
Source | SS df MS Number of obs = 1171
-------------+------------------------------ F( 1, 1169) = 0.65
Model | 1.17274119 1 1.17274119 Prob > F = 0.4217
Residual | 2121.80591 1169 1.81506066 R-squared = 0.0006
-------------+------------------------------ Adj R-squared = -0.0003
Total | 2122.97865 1170 1.81451167 Root MSE = 1.3472
------------------------------------------------------------------------------
base_age | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
won_lottry | -.0632965 .0787452 -0.80 0.422 -.2177941 .0912012
_cons | 12.03627 .0559895 214.97 0.000 11.92642 12.14612
------------------------------------------------------------------------------
reg male won_lottry
Source | SS df MS Number of obs = 1171
-------------+------------------------------ F( 1, 1169) = 0.00
Model | .000164554 1 .000164554 Prob > F = 0.9796
Residual | 292.724003 1169 .250405477 R-squared = 0.0000
-------------+------------------------------ Adj R-squared = -0.0009
Total | 292.724167 1170 .250191596 Root MSE = .50041
------------------------------------------------------------------------------
male | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
won_lottry | .0007498 .0292483 0.03 0.980 -.0566352 .0581348
_cons | .5043178 .0207961 24.25 0.000 .4635159 .5451197
------------------------------------------------------------------------------
Naive OLS estimate of the model shown in Table 11.2 on page 273.
reg finish8th use_fin_aid base_age male
Source | SS df MS Number of obs = 1171
-------------+------------------------------ F( 3, 1167) = 26.53
Model | 16.230726 3 5.41024199 Prob > F = 0.0000
Residual | 237.957148 1167 .203905011 R-squared = 0.0639
-------------+------------------------------ Adj R-squared = 0.0614
Total | 254.187874 1170 .217254593 Root MSE = .45156
------------------------------------------------------------------------------
finish8th | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
use_fin_aid | .1209084 .0268012 4.51 0.000 .0683244 .1734924
base_age | -.062961 .0098456 -6.39 0.000 -.0822779 -.043644
male | -.0858505 .0264754 -3.24 0.001 -.1377952 -.0339057
_cons | 1.410283 .1206031 11.69 0.000 1.17366 1.646906
------------------------------------------------------------------------------
Instrumental-variables (2SLS) from Table 11.2 on page 273.
ivreg finish8th base_age male (use_fin_aid=won_lottry), first
First-stage regressions
-----------------------
Source | SS df MS Number of obs = 1171
-------------+------------------------------ F( 3, 1167) = 346.26
Model | 134.199092 3 44.7330305 Prob > F = 0.0000
Residual | 150.76248 1167 .129188072 R-squared = 0.4709
-------------+------------------------------ Adj R-squared = 0.4696
Total | 284.961571 1170 .243556899 Root MSE = .35943
------------------------------------------------------------------------------
use_fin_aid | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
base_age | -.0151604 .007826 -1.94 0.053 -.0305151 .0001943
male | -.0202571 .02107 -0.96 0.337 -.0615965 .0210823
won_lottry | .674527 .0210141 32.10 0.000 .6332974 .7157567
_cons | .4327598 .0951594 4.55 0.000 .2460573 .6194624
------------------------------------------------------------------------------
Instrumental variables (2SLS) regression
Source | SS df MS Number of obs = 1171
-------------+------------------------------ F( 3, 1167) = 25.21
Model | 15.8188369 3 5.27294563 Prob > F = 0.0000
Residual | 238.369037 1167 .204257958 R-squared = 0.0622
-------------+------------------------------ Adj R-squared = 0.0598
Total | 254.187874 1170 .217254593 Root MSE = .45195
------------------------------------------------------------------------------
finish8th | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
use_fin_aid | .1590002 .0391733 4.06 0.000 .0821423 .2358581
base_age | -.0621574 .0098725 -6.30 0.000 -.0815271 -.0427876
male | -.0851448 .0265036 -3.21 0.001 -.1371449 -.0331448
_cons | 1.378128 .1230896 11.20 0.000 1.136626 1.619629
------------------------------------------------------------------------------
Instrumented: use_fin_aid
Instruments: base_age male won_lottry
------------------------------------------------------------------------------