Re: st: Generate a new variable [four firm concentration ratio]

["ALICE DOBSON" <alice_dobson@hotmail.com>]

Thanks Nick. It works selectively as I am not getting "firstfour" for all 
rows.
This is probably because the rows have values for one to seven firms and not 
for all seven firms
Further, I checked the data editor and see that in such cases where the data 
is avaiable for less than seven firms the command arranges the top four 
values s1-s4 (arbitrarily) in columns for say s3-s6
Hence, I do not get firstfour for all such cases
Best,
Alice



> From: n j cox <n.j.cox@durham.ac.uk>
> Reply-To: statalist@hsphsun2.harvard.edu
> To: statalist@hsphsun2.harvard.edu
> Subject: Re: st: Generate a new variable [four firm concentration ratio]
> Date: Mon, 21 Nov 2005 21:31:19 +0000
>
> If the number of consumers is integer, then
> just install -rowsort- from SSC.
>
> rowsort F?_mt, gen(s1-s7) descend
> gen firstfour = 100 * (s1 + s2 + s3 + s4) / CONSUM_mt
>
> Nick
> n.j.cox@durham.ac.uk
>
> ALICE DOBSON
>
> I use stata 9.1
>
> I have an unbalanced panel data of the type:
>
> geographical region (m = 1..1154)
> year (t = 1..7)
>
> with the following variables:
>
> total number of consumers in each region (CONSUM_mt)
> total number of consumers of seven firms in each region (F1_mt, F2_mt, 
> F3_mt, F4_mt, F5_mt, F6_mt, F7_mt)
>
>
> I want to calculate the four firm concentration ratio for each region, 
> C4_mt, which is the proportion of the number of consumers of top four firms 
> to the total number of consumers in that region, in percentage
>
> Could anyone be kind enough to help me with this simple calculation?
>
> GEOGREGN YEAR CONSUM F1 F2 F3 F4 F5 F6 F7 C4
> M1 1969
> M1 1970
> M1 1971
> M1 1972
> M1 1973
> M1 1974
> M1 1975
> M2 1969
> M2 1970
> M2 1971
> M2 1972
> .
> .
> .
> .
> .
> .
> .
> .
>
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