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Re: st: Newey estimations


From   "Clive Nicholas" <Clive.Nicholas@newcastle.ac.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Newey estimations
Date   Thu, 3 Aug 2006 00:51:30 +0100 (BST)

Evelyn Colino de Cantero wrote:

[...]

> Does somebody knows what is the exactly procedure Stata
> follows to test parameters under linear reg. with Newey-West
> std. errors estimators?

Why use a wimpish, water-pistol version of OLS Newey-West in Stata when
you can use a OLS Newey-West package that's chock-full with AK47s, Desert
Eagles and Kalashnikovs? An example:

. webuse grunfeld

. ivreg2 invest mvalue kstock, bw(2) robust small

OLS regression with robust standard errors
------------------------------------------
Heteroskedasticity and autocorrelation-consistent statistics
  kernel=Bartlett; bandwidth=2
  time variable (t):  year
  group variable (i): company

                                                    Number of obs =      200
                                                    F(  2,   197) =   113.16
                                                    Prob > F      =   0.0000
Total (centered) SS     =  9359943.917              Centered R2   =   0.8124
Total (uncentered) SS   =  13620706.07              Uncentered R2 =   0.8711
Residual SS             =  1755850.432              Root MSE      =    94.41
----------------------------------------------------------------------------
           |               Robust
    invest |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-----------+----------------------------------------------------------------
    mvalue |   .1155622   .0085916    13.45   0.000     .0986189    .1325054
    kstock |   .2306785    .058479     3.94   0.000     .1153533    .3460037
     _cons |  -42.71437   14.04683    -3.04   0.003    -70.41583   -15.01291
----------------------------------------------------------------------------

. ivreg2 invest mvalue kstock time, bw(2) robust small

OLS regression with robust standard errors
------------------------------------------
Heteroskedasticity and autocorrelation-consistent statistics
  kernel=Bartlett; bandwidth=2
  time variable (t):  year
  group variable (i): company

                                                    Number of obs =      200
                                                    F(  3,   196) =    79.84
                                                    Prob > F      =   0.0000
Total (centered) SS     =  9359943.917              Centered R2   =   0.8127
Total (uncentered) SS   =  13620706.07              Uncentered R2 =   0.8713
Residual SS             =   1753085.77              Root MSE      =    94.57
----------------------------------------------------------------------------
            |               Robust
    invest |      Coef.   Std. Err.      t    P>|t|     [95% Conf. Interval]
-----------+----------------------------------------------------------------
    mvalue |   .1163783   .0085026    13.69   0.000     .0996099    .1331467
    kstock |   .2213351   .0667831     3.31   0.001     .0896294    .3530408
      time |   .7737904   1.782941     0.43   0.665    -2.742421    4.290002
     _cons |  -49.14306   15.96811    -3.08   0.002    -80.63443   -17.65169
----------------------------------------------------------------------------

> Is still valid to use the "test" command for this pourpose?

Yes:

. test time

 ( 1)  time = 0

       F(  1,   196) =    0.19
            Prob > F =    0.6648

All of which is to say, download -ivreg2- from SSC. The -bw(2)- option is
Newey-West.

Hope all that helps. :)

CLIVE NICHOLAS        |t: 0(044)7903 397793
Politics              |e: clive.nicholas@ncl.ac.uk
Newcastle University  |http://www.ncl.ac.uk/geps

Whereever you go and whatever you do, just remember this. No matter how
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