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Re: st: draw a sample from variables and incidence rates


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: draw a sample from variables and incidence rates
Date   Wed, 18 Mar 2009 12:37:15 +0000 (GMT)

--- On Wed, 18/3/09, moleps islon <moleps2@gmail.com> wrote:
> -Is there an easy way to draw 40 random patients from a
> sample of 450 and generate a dummy variable containg 0 "not
> drawn" 1"drawn". E.g a command like : draw variable 40, 
> gen(dummy)

When you want to create a dummy you implicitly assume that 
you want to draw without replacement. There is an easy way
of doing this with replacement (as this is part of the 
bootstrap): -bsample- with the -weight()- option. If you
realy want to sample without replacement you can adjust
the code below:

*---------- begin example ------------
sysuse auto, clear

// sort will store the original sort order
gen long sort  = _n

// create your draw variable where you
// sample 40 respondents (cars) without
// replacement
gen u = runiform()
sort u
gen byte draw = _n <= 40

// restore the orginal sort order
sort sort

// clean up 
drop u sort
*---------- end example ---------------
(For more on how to use examples I sent to the Statalist, see
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )

-- Maarten

-----------------------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://home.fsw.vu.nl/m.buis/
-----------------------------------------


      

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