--- 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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