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Re : st: RES: relevance of instruments


From   donsaane dontsi <donsaane@yahoo.fr>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re : st: RES: relevance of instruments
Date   Wed, 2 May 2012 15:46:43 +0100 (BST)

Thanks Henrique, 
So if the Cragg-Donald statistic is higher than the critical values of Stock and Yogo, we should say that our instruments are stong , even if the partial R2 is small?
Thanks

donsaane


----- Mail original -----
De : Henrique Neder <hdneder@ufu.br>
À : statalist@hsphsun2.harvard.edu
Cc : 
Envoyé le : Mardi 1 mai 2012 23h22
Objet : st: RES: relevance of instruments

I think that you have to do a more detailed inspection of the problem. See
Stock and Yogo critical values approach in the help for ivreg2 (Tests of
under- and weak identification).

Henrique Neder

-----Mensagem original-----
De: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] Em nome de donsaane dontsi
Enviada em: Tuesday, May 01, 2012 6:28 PM
Para: statalist@hsphsun2.harvard.edu
Assunto: st: relevance of instruments

Hi,
I run an ivreg2 regression , and I want to know if my instruments are
strong. Here is the ouptut below: My question is: Is my instruments are
strong because F=16.46 >10? Or there are not because Partial R2 are small?
thanks

. ivreg2 emploi c30a d30a d30b e30 g30a j30a j30c j30e l30a l30b a2 a4a a6a
a7 b2a b2b b2c b5 (k30=  fin1k21 fink21),  ffirst robust First-stage
regressions
-----------------------
Summary results for first-stage regressions:
                Shea
Variable      Partial R2      Partial R2       F(  2,   254)    P-value
k30             0.0149          0.0149             16.46         0.0000
NB: first-stage F-stat heteroskedasticity-robust
 
IV (2SLS) regression with robust standard errors
------------------------------------------------
                                                      Number of obs =     
275
                                                      F( 19,   255) =    
0.81
                                                      Prob > F      =  
0.7000 Total (centered) SS     =  82.96736373                Centered R2  
=  -0.2291 Total (uncentered) SS   =  88.98325588                Uncentered
R2 =  -0.1460 Residual SS             =   101.976442                Root
MSE      =      .61
----------------------------------------------------------------------------
--
             |               Robust
      emploi |      Coef.   Std. Err.      z    P>|z|     [95% Conf.
Interval]
-------------+----------------------------------------------------------
-------------+------
         k30 |  -.3825684   .2103571    -1.82   0.069    -.7948607   
.0297239
        c30a |  -.0519788    .041202    -1.26   0.207    -.1327332   
.0287757
        d30a |    .108799   .0397846     2.73   0.006     .0308226   
.1867754
        d30b |   .0031931   .0348354     0.09   0.927    -.0650831   
.0714693
         e30 |   -.036257   .0293068    -1.24   0.216    -.0936972   
.0211832
        g30a |   .1152195    .058208     1.98   0.048     .0011339   
.2293052
        j30a |   .0429871   .0402775     1.07   0.286    -.0359552   
.1219295
        j30c |   .0356038   .0411333     0.87   0.387    -.0450161   
.1162236
        j30e |  -.0100979    .027043    -0.37   0.709    -.0631013   
.0429054
        l30a |  -.0212033   .0367756    -0.58   0.564    -.0932822   
.0508756
        l30b |   .0310033   .0326002     0.95   0.342    -.0328918   
.0948985
          a2 |  -.0603592   .0425782    -1.42   0.156     -.143811   
.0230925
         a4a |  -.0009478   .0028646    -0.33   0.741    -.0065624   
.0046668
         a6a |   .0933522   .0763294     1.22   0.221    -.0562506    
.242955
          a7 |   .1954874   .1460382     1.34   0.181    -.0907422   
.4817169
         b2a |   .0040452   .0023674     1.71   0.087    -.0005947   
.0086851
         b2b |   .0011903    .002382     0.50   0.617    -.0034784   
.0058591
         b2c |  -.0013251    .006618    -0.20   0.841    -.0142962   
.0116459
          b5 |  -.0002381   .0035678    -0.07   0.947     -.007231   
.0067547
       _cons |   .5296318   7.086394     0.07   0.940    -13.35945   
14.41871
----------------------------------------------------------------------------
--
Hansen J statistic (overidentification test of all instruments):        
0.418
                                                   Chi-sq(1) P-val =  
0.51788
----------------------------------------------------------------------------
--
Instrumented:  k30
Instruments:   fin1k21 fink21 c30a d30a d30b e30 g30a j30a j30c j30e l30a
l30b
               a2 a4a a6a a7 b2a b2b b2c b5
----------------------------------------------------------------------------
--

 
 

donsaane

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