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st: sampling by id, was Re: statalist-digest V4 #1555


From   "Michael Blasnik" <michael.blasnik@verizon.net>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: sampling by id, was Re: statalist-digest V4 #1555
Date   Sun, 21 Mar 2004 09:35:45 -0500

One approach (assuming that your data "mydata.dta" is already sorted by id):

use mydata
keep id
bysort id: keep if _n==1
sample 5
sort id
merge id using mydata, nokeep
drop _merge
save mysample


Michael Blasnik
michael.blasnik@verizon.net

----- Original Message ----- 
From: "Carlos Elordi" <celordi@wirthlin.com>
To: <statalist@hsphsun2.harvard.edu>
Sent: Saturday, March 20, 2004 4:57 PM
Subject: st: Re: statalist-digest V4 #1555


> Hi,
> I would like to create a random sample of observations from a large data
> file (lets say 1 or 5%), selecting cases based on an id number. For many
> cases I have more than one row (record) per id number, so I cannot apply
the
> sample command directly.
> Is there an easy way to randomly select all the cases, together with their
> corresponding records, without having to reshape the data? The number of
> records for each case could range from 1 to 15.
> Thanks in advance for any help,
> Carlos
>
>
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