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Re: st: RE: Computing Herfindahl-Hirschman index
From
Syed Basher <[email protected]>
To
[email protected]
Subject
Re: st: RE: Computing Herfindahl-Hirschman index
Date
Fri, 10 Dec 2010 11:52:06 -0800 (PST)
Dear Nick,
Sorry about the delay to thank your assistance. I am glad to know other variations of the HH index, and the helpful -ineq- routine. Thank you very much.
Syed Basher
Qatar National Food Security Program
--- On Wed, 12/8/10, Nick Cox <[email protected]> wrote:
> From: Nick Cox <[email protected]>
> Subject: st: RE: Computing Herfindahl-Hirschman index
> To: "'[email protected]'" <[email protected]>
> Date: Wednesday, December 8, 2010, 3:20 PM
> The (minor) bad news is that the data
> structure here is not helpful for this purpose, as Antoine
> Terracol implies in his reply, although the -reshape- is one
> line.
>
> The good news is that this beast has often been programmed,
> often under a different name. It, or its complement in 1, is
> also known (e.g.) as Simpson's index, especially in ecology,
> as heterozygosity and as one of several things called the
> Gini index. Invoking the name Herfindahl gets nods in
> economics, but he was not the first discoverer. (Hirschman
> as I recall proposed not this formula, but something else.)
>
>
> Using e.g. -ineq- from SSC I imagine code like this:
>
> reshape long item, i(importer)
> ineq item, by(importer) gensim(herfindahl)
>
> You can -reshape- back if desired.
>
> Nick
> [email protected]
>
>
> Syed Basher
>
> I have the following (hypothetical) trade dataset which
> contains imported items by importer.
>
> importer | item1 item2..... item20
> -----------------------------------
> 11 | 10 20 80
> 12 | 5 7 9
> 13 | 1
> 14 |
> 2 6
> ... |
> 20 | 8 9
>
> I would like to obtain the following table/data:
>
> importer | item1 item2 .... item20
> -------------------------------------------
> 11 | 1600 2921.84
> 7091.41
> 12 | 400 357.92
> 89.75
> 13 |
> 7.30
> 14 | 64
> 39.88
> ... |
> 20 | 1024 591.67
>
>
> where, say, the value 1600 is obtained using the formula
> (si*100)^2, where si is the share of importer11 in item1 and
> is obtained using 10/25, 25 is the sum of all entries in
> item1. This will allow me to get the
> Herfindahl-Hirschman index by importer for each item.
>
>
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