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RE: st: RE: question on keeping observations - selecting substitute instituions for sampled institutions


From   "Martin Weiss" <[email protected]>
To   <[email protected]>
Subject   RE: st: RE: question on keeping observations - selecting substitute instituions for sampled institutions
Date   Wed, 6 Jan 2010 13:55:07 +0100

<>

I could imagine that you can drop the first line -gen int school=_n- as well, then. Note the "_n" in the first line is unrelated to the one in the square brackets in the second one...

HTH
Martin


-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of Gáti Annamária
Sent: Mittwoch, 6. Januar 2010 13:46
To: [email protected]
Subject: Re: st: RE: question on keeping observations - selecting substitute instituions for sampled institutions

Dear Martin,

The following lines of your syntax solved my problem completely:

gen int school=_n
gen byte substitute=minta[_n+1] | minta[_n-1]

I already had the sample so I only needed to mark the substitutes somehow.
I see the overlapping substitutes, it is a further step to decide how to 
handle them.
Thank you very much for your kind and fast help,

annamaria

**
**
**

Martin Weiss írta:
> <>
> 
> You can -generate- a dummy for "being a substitute". What do you want to happen for adjacent sampled schools? Their substitutes must overlap, such as 324 and 325 in my example:
> 
> *******
> vers 11
> 
> clear*
> set obs 4000
> set seed 43532
> 
> gen int school=_n
> 
> gen randomnumber=runiform()
> sort randomnumber
> gen sampled=_n<=300
> 
> sort school
> 
> gen byte substitute=sampled[_n+1] | sampled[_n-1]
> 
> //problem: sometimes sampled schools adjacent to each other
> cou if substitute
> l in 322/326
> 
> *******
> 
> 
> HTH
> Martin
> 
> 
> -----Original Message-----
> From: [email protected] [mailto:[email protected]] On Behalf Of Gáti Annamária
> Sent: Mittwoch, 6. Januar 2010 12:56
> To: [email protected]
> Subject: st: question on keeping observations - selecting substitute instituions for sampled institutions
> 
> Dear List users,
> 
> I am trying to collect a sample out of schools. I have successfully 
> sampled 300 institutions out of 4000. I have now a dataset containing 
> 4000 observations and a variable named sample indicating whether a given 
> institution is part of my sample (code=1) or not (code=0).
> 
> As I also need 2 substitutes for each institutions I would like to chose 
> the ones that are right above and under the sampled school. Is there a 
> simple way to do this with stata? I was browsing through the Keep 
> observations commands but didn’t manage to find out how to do this.
> 
> Thank U in advance
> 
> Annamaria
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