<>
You want to read through Nick`s seminal
http://www.stata-journal.com/sjpdf.html?articlenum=pr0004 to get a grip on
these issues :-)
HTH
Martin
-----Ursprüngliche Nachricht-----
Von: [email protected]
[mailto:[email protected]] Im Auftrag von Sandu Cojocaru
Gesendet: Montag, 2. November 2009 23:43
An: [email protected]
Betreff: Re: st: AW: loop question
Martin,
Thanks much, this is very elegant indeed!
cheers,
sandu
On Mon, Nov 2, 2009 at 5:47 PM, Martin Weiss <[email protected]> wrote:
> <>
>
>
> *************
> clear*
>
> inp byte(group_id member_id) C
> 1 1 300
> 1 2 200
> 1 3 100
> 2 1 150
> 2 2 200
> 2 3 100
> 2 4 50
> end
>
> compress
> l, noo sepby(group_id)
>
> bys group_id (C): /*
> */ gen diff=C[_n+1]-C[_n]
> bys group_id: gen num=_N-_n
> bys group_id (num): /*
> */ gen outcome_var=sum(diff*num)
> sort group_id member_id
>
> drop diff num
> l, noo sepby(group_id)
> *************
>
>
> HTH
> Martin
>
> -----Ursprüngliche Nachricht-----
> Von: [email protected]
> [mailto:[email protected]] Im Auftrag von Sandu
Cojocaru
> Gesendet: Montag, 2. November 2009 20:35
> An: [email protected]
> Betreff: st: loop question
>
> Dear All:
>
> I'm having trouble generating a variable that for each member i equals
> sum(Cj-Ci) over all Cj>Ci where i and j are members of the same group.
> Here's an example of the data setup - I'm trying to calculate
> `outcome_var'.
> For row 1 outcome_var=0, for row 3 = (200-100)+(300-100) = 300...and so
> on...
>
> group_id member_id C outcome_var
> 1 1 300 0
> 1 2 200 100
> 1 3 100 300
> 2 1 150 50
> 2 2 200 0
> 2 3 100 150
> 2 4 50 300
> 3 1 and so on...
>
> Any help would be greatly appreciated!
> sandu
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