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Re: st: RE: Changing positive values to negative in Stata


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: Changing positive values to negative in Stata
Date   Thu, 20 Apr 2006 22:02:36 +0100 (BST)

Lets call this other variable which captures the common charecteristics scott, and suzy has to be
negative if scott is larger than 2 and less than pi or is equal to e to the power pi. Than you
would code:

replace suzy = -suzy if suzy > 0 & ( scott > 2 & scott < c(pi) ) | scott == exp(1)^c(pi)

--- Suzy <scott_788@wowway.com> wrote:

> Thanks Nick - I neglected to state that  have over 600 observations with 
> all different positive values (as well as negative values and missing 
> values) within the subgroup of total observations of the variable, so 
> this code could be somewhat inefficient.  Also,  it is difficult to 
> specify which observations, for example, by id  - thus  the next best 
> thing in this instance seems to be to sort by their common 
> characteristic - which  is captured by another variable.
> 
> Nick Cox wrote:
> 
> >replace suzy = -suzy if suzy > 0 & <whatever> 
> >
> >So if suzy is positive, it is negated. The 
> >crunch is specifying the extra condition <whatever> 
> >that catches just the observations desired. 
> >
> >Sorting is a red herring here. So long as you 
> >can specify which observations you want, sort order
> >is immaterial. 
> >
> >Nick 
> >n.j.cox@durham.ac.uk 
> >
> >Suzy
> > 
> >  
> >
> >>I have a continuous variable with positive, negative, and zero values 
> >>and also missing values(.). 
> >>I would like to know if anyone has an easy Stata code/command 
> >>to change 
> >>just the positive values to a negative (change the sign: 4.4567 to 
> >>-4.4567) for just a particular subgroup of the total (n=661 
> >>out of over 
> >>N=4,000). Within this subgroup (which I can sort, but not by 
> >>id) there 
> >>already are a few appropriately negative values in place.
> >>    
> >>
> >
> >*
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> >
> >
> >
> >  
> >
> 
> 
> *
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> 


-----------------------------------------
Maarten L. Buis
Department of Social Research Methodology
Vrije Universiteit Amsterdam
Boelelaan 1081
1081 HV Amsterdam
The Netherlands

visiting adress:
Buitenveldertselaan 3 (Metropolitan), room Z214

+31 20 5986715

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


		
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