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Re: st: draw overlapping normal densities


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: draw overlapping normal densities
Date   Tue, 13 Jul 2010 13:34:36 -0700 (PDT)

--- On Tue, 13/7/10, Cohen, Elan wrote:
> I'd like to draw two overlapping Normal densities based on
> 2 sets of population means and sds.  For example:
> 
> sysuse auto
> su price if !foreign , meanonly
> local mean0 = r(mean)
> local sd0 = r(sd)
> su price if foreign , meanonly
> local mean1 = r(mean)
> local sd1 = r(sd)
> 
> This is where I'd like to draw a normal curve based on
> (mean0, sd0) and another based on (mean1, sd1).  

If you add the -meanonly- option you will not compute the
standard deviation, so the locals sd0 and sd1 will contain
nothing in your example. Otherwise you were looking in the
right direction. To comple the example:

*------------------ begin example -------------------
sysuse auto
su price if !foreign 
local mean0 = r(mean)
local sd0 = r(sd)
su price if foreign 
local mean1 = r(mean)
local sd1 = r(sd)
twoway function y = normalden(x, `mean0',`sd0'), ///
                range(3000 15000) ||             ///
       function y = normalden(x, `mean1',`sd1'), ///
                range(3000 15000) 
*----------------- end example -----------------------

Hope this helps,
Maarten

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

http://www.maartenbuis.nl
--------------------------


      

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