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Re: st: Question


From   Gao Liu <gao.liu@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Question
Date   Tue, 21 Apr 2009 02:17:34 -0400

Dear Zhu, Yi:

Here is one way:

sort firm_name alliance_date

qui forval i = 1/`=_N' {
	count if firm_name  == firm_name [`i'] &
inrange(alliance_date-alliance_date[`i'] , 1, (5*365+1))
	replace alliance_no= r(N) in `i'
}


It may take a while, as it has to run through all observations one by
one, but it should work.

Best

Gao



2009/4/21 朱琦 <cs_thomaszhu@hotmail.com>
>
> Question
>
> Dear Stata List!
>
> I am working on a project that examines a firm's international strategic alliance (ISA).
>
> In my huge dataset, I have around 2000 firms forming ISA between 01/01/1989- 0/01/1999. Each firm is likely to form multiple international strategic alliances during this period.
> For example: Firm A  forms the first strategic alliance on 01/02/1989; the second on 04/09/1990; the third on 06/09/1997.
>
> What I need to record is the number of new strategic alliances that the firm forms within 5 years after the focal one.
> For firm A, the number of new strategic alliances that Firm A forms within 5 years is 1 corresponding to its first strategic alliance on  01/02/1989;
>                 the number of new strategic alliances that Firm A forms within 5 years is 0 corresponding to  its second strategic alliance on 04/09/1990 ;
>                the number of new strategic alliances that Firm A forms within 5 years is 0 corresponding to  its third strategic alliance on 06/09/1997;
>
> As it is a huge dataset, I can't do it by hand. How can I do it by using STATA? Thanks!
>
>
>
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