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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 13:28:23 +0100 
if you just want the hhi variables, you could either
. drop item*
at the end of the code
or
. drop item
. reshape wide hhi , i(importer) j(id_item)
within the code (i.e drop item before reshaping back, and ommit the item 
variable from the -reshape- command)
Antoine
On 08/12/2010 13:19, Syed Basher wrote:
Dear Antoine,
The second option is better and worked.
. reshape wide item hhi , i(importer) j(id_item)
The above command reports "item" and the associated "hhi" for all items. Suppose I want only the hhi, deleting item from the above reshape command doesn't work.
Thank you very very much.
Syed
--- On Wed, 12/8/10, Antoine Terracol<[email protected]>  wrote:
From: Antoine Terracol<[email protected]>
Subject: Re: st: Computing Herfindahl-Hirschman index
To: [email protected]
Date: Wednesday, December 8, 2010, 2:35 PM
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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suspect n'a ete trouve.
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