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From |
natasha agarwal <agarwana2@googlemail.com> |

To |
statalist@hsphsun2.harvard.edu |

Subject |
Re: st: RE: RE: estimation with a time trend. |

Date |
Mon, 5 Jul 2010 16:19:15 +0100 |

I am really really sorry for this confusion what I have created here. I wanted to introduce a time trend in my estimation where my years go from 2001-2005. I was estimating an augmented production function using an unbalanced panel data using a within estimator. With time trend I mean: panel identifier year time trend 1 2001 1 1 2002 2 1 2003 3 1 2004 4 1 2005 5 2 2001 1 2 2002 2 The only way I knew how to do it was to use the egen -group- command.That is why I wanted to do the egen-group- command. However I was not confident whether the creation of the same was correct because of the unbalanced nature of the data. for the purpose of estimating my equation I issue the following command: egen t=group(year) xtreg lnrval lnk lnw lnvfdi t, fe vce(robust) Thanks Natasha On Mon, Jul 5, 2010 at 3:52 PM, Maarten buis <maartenbuis@yahoo.co.uk> wrote: > --- On Mon, 5/7/10, natasha agarwal wrote: >> I was wondering then what is the point in doing this then? > > > This thread is getting very confused. Let me try > to reconstruct the argument: > > You asked about estimating a time trend by first > creating a variable using -egen group()-. Now > we had to guess why you would want to do that. > We guessed that you wanted to make sure that your > time has the value 0 at some a meaningful point > in time. Which in general is good, though it > doesn't matter if you used a fixed effects model > without interactions (it does matter if you > include interactions with time). > > Even though making sure that time has a meaningful > 0 value is a good idea, using -egen group()- for > that is a very dangerous idea, and you should never > do that. Instead you should just substract some > meaningful 'midpoint' or 'reference year'. > > So, to clear up this thread: > Why did you want to use -egen group()-? > > -- Maarten > > -------------------------- > Maarten L. Buis > Institut fuer Soziologie > Universitaet Tuebingen > Wilhelmstrasse 36 > 72074 Tuebingen > Germany > > http://www.maartenbuis.nl > -------------------------- > > > > > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ > * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**Follow-Ups**:**Re: st: RE: RE: estimation with a time trend.***From:*Maarten buis <maartenbuis@yahoo.co.uk>

**References**:**Re: st: RE: RE: estimation with a time trend.***From:*natasha agarwal <agarwana2@googlemail.com>

**Re: st: RE: RE: estimation with a time trend.***From:*Maarten buis <maartenbuis@yahoo.co.uk>

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