Yes, I also think MAARTEN did a good job here...
-------- Original-Nachricht --------
> Datum: Tue, 23 Dec 2008 16:48:55 +0100
> Von: Choudry T Shehzad <[email protected]>
> An: [email protected]
> Betreff: Re: st: Fixing the value in egen command
> Thanks Martin...It works well
>
> Maarten buis wrote:
> > --- Maarten buis wrote:
> >
> >>> bys country (year): gen initgdp = gdp[_n==1]
> >>> bys country (year): replace initgdp = sum(initgdp)
> >>>
> >
> > --- Choudry T Shehzad <[email protected]> wrote:
> > <snip>
> >
> >> When I use your command
> >>
> >> bys country (year): gen initgdp = gdp[_n==1980]
> >> bys country (year): replace initgdp = sum(initgdp)
> >>
> >> all values of initgdp become zeros
> >>
> >
> > _n refers to the observation number and not to the value a variable may
> > take. So, the first observation is _n == 1 and not _n == 1980 (which is
> > the 1980th observation, which is missing, and -sum()- treats missings
> > as zeros, which is why you ended up with all zeros).
> >
> > -- Maarten
> >
> >
> > -----------------------------------------
> > Maarten L. Buis
> > Department of Social Research Methodology
> > Vrije Universiteit Amsterdam
> > Boelelaan 1081
> > 1081 HV Amsterdam
> > The Netherlands
> >
> > visiting address:
> > Buitenveldertselaan 3 (Metropolitan), room N515
> >
> > +31 20 5986715
> >
> > http://home.fsw.vu.nl/m.buis/
> > -----------------------------------------
> >
> >
> >
> > *
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> >
>
>
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