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st: RE: graph symbol proportional to N


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   st: RE: graph symbol proportional to N
Date   Wed, 2 Apr 2003 13:53:24 +0100

S.E.Korupp
> 
> a few years ago I saw a Stata graph where the symbols 
> (triangles) in the
> (twoway) graph were sized proportional to the underlying N of that
> particular point of the function. I looked everywhere in 
> 'Graphics' but
> I just can't seem find the according command. Can someone give me a
> hint? By the way I'm using Stata6.

You should use weights. However, it is not as simple as stated.

Even in principle, scaling symbol length means that 
symbol area increases as the square of that, and scaling
symbol area means that symbol length increases as the 
square root of that. I seem to recollect psychological 
evidence that what the eye-and-brain usually perceive 
is somewhere in between a linear-based perception 
and an area-based perception, perhaps using a power law
of symbol area with exponent ~0.7. 

Be that as it may, see Graphics (Release 6) pp.149ff 
for what Stata does. 

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