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RE: st: histogram with normal distribution modified


From   "Nick Cox" <n.j.cox@durham.ac.uk>
To   <statalist@hsphsun2.harvard.edu>
Subject   RE: st: histogram with normal distribution modified
Date   Mon, 10 Mar 2008 09:37:30 -0000

Note the simple but crucial detail: you must specify an sd as well as a
mean for 
a superimposed normal. You could use that of the data, but you must
specify one. 

Nick 

Maarten buis

--- Ana Gabriela Guerrero Serdan <ag_guerreroserdan@yahoo.com> wrote:
> Sorry, my mean (not median) is -1 so I want a
> hypothetical normal distribution to be centered around
> 0 not -1. The reason is that I would like to compare
> the distribution of my sample to a hypothetical
> distribution.  So I want to plot both distributions in
> the histogram. 

What about this:

*-------------------- begin example ------------------------
sysuse auto, clear
sum mpg
local sd = r(sd)
hist mpg,                                              ///
   plot(function y = normden(x,30,`sd'), range(12 41)) ///
   legend(order(1 "density"                            ///
                2 "theoretical" "normal"))
*-------------------- end example --------------------------
(For more on how to use examples I sent to the Statalist, see
http://home.fsw.vu.nl/m.buis/stata/exampleFAQ.html )

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