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From |
"ALICE DOBSON" <alice_dobson@hotmail.com> |

To |
statalist@hsphsun2.harvard.edu |

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

Date |
Mon, 21 Nov 2005 18:27:49 -0500 |

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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**References**:**Re: st: Generate a new variable [four firm concentration ratio]***From:*n j cox <n.j.cox@durham.ac.uk>

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