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Re: st: Computing Herfindahl-Hirschman index
From
Antoine Terracol <[email protected]>
To
[email protected]
Subject
Re: st: Computing Herfindahl-Hirschman index
Date
Wed, 08 Dec 2010 12:35:19 +0100
Syed,
try
egen sum_item1=total(item1)
gen hhi_item1=(100*item1/sum_item1)^2
and so on for each item
or, alternatively
reshape long item, i(importer) j(id_item)
bysort id_item : egen sum=total(item)
gen hhi=item/sum
drop sum
reshape wide item hhi , i(importer) j(id_item)
which should give you all the results at once (I've not checked the code)
Antoine
On 08/12/2010 12:11, Syed Basher wrote:
Dear Statalist,
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.
I hope any one of you can help. Thank you so mcuh.
Regards,
Syed Basher
Qatar National Food Security Program
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