Re: st: AW: Question on xtreg and the FE option

[Klaus Pforr <kpforr@googlemail.com>]

For your problem, a good solution is -- as clivelist recommended -- to 
use your xtreg, fe with time dummies.
A simple example would be:

webuse nlswork, clear
xtset idcode
xtreg ln_wage age ttl_exp i.year, fe

this is a candidate of a simple answer to your presumably simple question.

best

Klaus

Am 08.11.2012 16:24, schrieb Andrew Nicholson:
> Ok got what looks like a couple mixed responses.  Heres my xtset
>
> xtset CountyNum QuarterYear
>
> Where CountyNum goes from 1 - 105 identifying all 105 individual counties in Kansas.  QuarterYear goes from 2001Q1 to 2008Q4 for each county.
>
> So for this xtset, using the fe option it will automatically generate County Level Fixed Effects and Quarter time fixed effects?  Or possibly just the County?
>
> Andrew Nicholson
>
> ----- Original Message -----
> From: "Klaus Pforr" <kpforr@googlemail.com>
> To: statalist@hsphsun2.harvard.edu
> Sent: Thursday, November 8, 2012 4:37:50 AM
> Subject: AW: st: AW: Question on xtreg and the FE option
>
> Linear fixed-effects-models can be understood as models on the deviances of the means, where the fixed-effect is the individual heterogeneity in the mean. Very often you are not interested in the deviance of a specific observation of a unit across time. All observation within a unit treated equally, i.e. they are symmetric with respect to time. Time becomes important, when you have/want to model correlation across time in the error term (help xtreg##correlation). I thing all of these options need the additional time specification in the xtset, but not the xtreg itself.
>
> Klaus
> __________________________________
>
> Klaus Pforr
> GESIS -- Leibniz Institut für Sozialwissenschaft
> B2,1
> Postfach 122155
> D - 68072 Mannheim
> Tel: +49 621 1246 298
> Fax: +49 621 1246 100
> E-Mail: klaus.pforr@gesis.org
> __________________________________
>
>
> -----Ursprüngliche Nachricht-----
> Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Justina Fischer
> Gesendet: Donnerstag, 8. November 2012 11:27
> An: statalist@hsphsun2.harvard.edu
> Betreff: Re: st: AW: Question on xtreg and the FE option
>
> How can stata use xtreg, fe without knowing the time dimension?
> -------- Original-Nachricht --------
> > Datum: Thu, 8 Nov 2012 10:21:07 +0000
> > Von: Nick Cox <njcoxstata@gmail.com>
> > An: statalist@hsphsun2.harvard.edu
> > Betreff: Re: st: AW: Question on xtreg and the FE option
> > This is not correct. There is no rule that a time variable _must_ be
> > specified.
> >
> > On Thu, Nov 8, 2012 at 10:11 AM, Justina Fischer <JAVFischer@gmx.de>
> > wrote:
> > > Hi Andrew
> > >
> > > when using xtset you have to specify both observational unit and
> > > time
> > dimension at the same time.
> > > E.g. xtset country year
> > >
> > > or xtset id timeline
> > >
> > >
> > > etc.
> > >
> > >
> > > Best
> > >
> > > Justina
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--
__________________________________
Klaus Pforr
GESIS -- Leibniz Institut für Sozialwissenschaft
B2,1
Postfach 122155
D - 68072 Mannheim
Tel: +49 621 1246 298
Fax: +49 621 1246 100
E-Mail: klaus.pforr@gesis.org
__________________________________

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