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RE: st: RE: resticting the sample?


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: RE: resticting the sample?
Date   Thu, 7 Oct 2004 10:52:04 +0100

I haven't got any gun in my hand, but 
I'm not clear that we need this syntax. 

Are you asking for what can be done by 

... if !inlist(_n,10,100,250) 

If that gets tedious, a macro assignment 
cuts the typing 

local outliers "inlist(_n,10,100,250)" 

regress <whatever> if !`outliers' 

Note that this could bite you. Sort 
the data and the observation numbers 
refer to different observations, but
then -suspendin()- as I understand it suffers from 
exactly the same problem. So I go 
back to my earlier suggestion 
to -generate- an in-sample indicate 
variable, or the other suggestions made. 

See also -inrange()-. 

Nick 
n.j.cox@durham.ac.uk 

Clive Nicholas
 
> Dimitriy V. Masterov replied to Shuaizhang Feng:
> 
> > Your can use preserve/restore to do this:
> 
> > preserve
> >         keep if age<40
> >         reg ....
> > restore
> 
> And Nick Cox replied to Shuaizhang Feng with:
> 
> > gen mysample = (age < 40) & (nobel_prize == 1) & 
> (extrasensoryperception
> > == 1)
> >
> > ...
> >
> > reg ... if mysample
> >
> > See also http://www.stata.com/support/faqs/data/trueorfalse.html
> 
> Running regressions using restricted samples (or by leaving out
> disqualifying observations) is something I've been really 
> keen to do for
> quite some time. But solutions such as the ones above seem to 
> be the only
> ones available (but that doesn't mean to say that they're bad).
> 
> I'm not really one for adding to StataCorp's burden, for they probably
> have enough to do in preparing for version 9. But wouldn't it 
> be great if
> one could run a regression in the following way:
> 
> . reg tomatoes potatoes onions sausages, suspendin(10 100 250)
> 
> so that you could simply suspend the observations without 
> having to -drop-
> them for that regression and then have to -restore- the dataset
> afterwards? Desirably, this option would automatically pick up the
> observation numbers as they appear by row in the data editor.
> 
> No doubt this idea will be shot down in myriad ways and 
> people would say
> that it couldn't work. But, to quote the British comedy duo 
> Armstrong and
> Miller, "Yes, but it would be good if it did."
> 
> CLIVE NICHOLAS        |t: 0(044)191 222 5969
> Politics              |e: clive.nicholas@ncl.ac.uk
> Newcastle University  |http://www.ncl.ac.uk/geps
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