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Re: st: Fixed Effects GLS
From
"Andrea Morescalchi" <[email protected]>
To
[email protected]
Subject
Re: st: Fixed Effects GLS
Date
Tue, 12 Apr 2011 10:56:50 +0200
Dear Ada and Maysa,
I was trying too to estimate the FEGLS as presented in
Wooldridge (2002), but with only one error component.
Anyway, I cannot understand properly the first line of
Ada's response: "Fixed Effects model is a kind of GLS
model. Use the basic FE commands and you will be fine."
I red carefully the Chapter 10 in Wooldridge, but I cannot
see among the - xtreg, FE - options available which is
that for doing FEGLS. In particular, the options available
for vce are: conventional, robust, cluster, bootstrap, or
jackknife.
FEGLS implies a particular structure for the (T-1)*(T-1)
covariance matrix for the errors, i.e. the matrix is
estimated after a standard FE in the first step where this
matrix is an identity matrix multiplicated for the
T-constant variance parameter.
Among FE Stata options the most proper to do FEGLS would
seem: "vce(conventional), the default, uses the
conventionally derived variance estimator for generalized
least squares regression". This line is a bit strange to
me since it seems to imply that the standard FE Stata
regression is actually a FEGLS! I computed the FE and the
FEGLS separately in Matlab and it turns out that the
"conventional" Stata FE is identical to that with error
v-c matrix equal to an identity matrix (multiplicated for
sigma_u). But which is the option which tells Stata to
estimate the v-c matrix in the first step?
Thanks in advance
Andrea
On Tue, 12 Apr 2011 00:09:11 +0000
"Ada Ma" <[email protected]> wrote:
Fixed Effects model is a kind of GLS model. Use the basic
FE commands and you will be fine.
There are user written commands for two way FEs but I
can't remember the commands' names, sorry! There are two
of them and they r both featured in the Stata Journal,
one of the authors for one command is Upward. HTH.
Sent using BlackBerry®
-----Original Message-----
From: May Ster <[email protected]>
Sender: [email protected]
Date: Mon, 11 Apr 2011 23:10:06
To: <[email protected]>
Reply-To: [email protected]: st:
Fixed Effects GLS
Dear Statalist,
I tried reading Woolridge (2002), Chapter 10 after he
mentioned
choosing between Random effects model and Fixed effects
model, he does
mentioned 'Fixed Effects GLS".
I'm not sure how does this apply to STATA command if i
want to use
'Fixed Effects GLS".
If my model is a two-way fixed effects model, Basically,
is the 'Fixed
Effects GLS" can be written like this (i've checked for
serial
correlation in error terms) ;
xi: xtgls var1 var2 var3 i.year , panel(hetero)
corr(psar1)
Please help.
Thank you very much in advance
Maysa
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