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st: RE: RE: RE: Re: RE: Multiple commands under "By varlist"?


From   "Apostolos Ballas" <aballas@aueb.gr>
To   statalist@hsphsun2.harvard.edu
Subject   st: RE: RE: RE: Re: RE: Multiple commands under "By varlist"?
Date   Sat, 26 Jun 2004 20:58:05 +0300

It is probably that I am dim, but since I have a very similar problem (ie,
many simulations which take hours) can some please explain how the following
example works.

Thanks a lot for the help.

Apostolos

-----Original Message-----
From: owner-statalist@hsphsun2.harvard.edu
[mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Nick Cox
Sent: Saturday, June 26, 2004 5:26 PM
To: statalist@hsphsun2.harvard.edu
Subject: st: RE: RE: Re: RE: Multiple commands under "By varlist"?


In this I referred to Michael Blasnik. 
14 seconds later he posted a similar point. 

Clearly this should be written up in supermarket 
trash newspapers as an Amazing Coincidence. 

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

Nick Cox
> 
> 2. The way -if- is implemented. The
> command 
> 
> 	regress returns factor if `i' == month
> 
> is implemented by testing every observation
> to see whether it should be included in
> the regression. In your case 99.9% of 
> the observations are irrelevant to each 
> regression, but Stata takes no special 
> action to avoid that. You should be 
> able to substitute -if- by -in-: 
> 
> gen long obsno = _n
> sort month port 
> forval i = 1/1000 { 
> 	local min = ...
> 	local max = ...
> 	regress returns factor in `min'/`max'	
> 	...
> } 
> 
> and by Blasnik's Law this should be much faster.

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