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Re: st: histogram with normal distribution modified


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: histogram with normal distribution modified
Date   Sun, 9 Mar 2008 20:09:10 +0000 (GMT)

--- Ana Gabriela Guerrero Serdan <ag_guerreroserdan@yahoo.com> wrote:
> I'm doing a histogram of z-scores. My distribution is 
> skewed to the left median is on -1. I would like to
> show the histogram and a normal distribution but the
> normal distribution going from the mean value 0 not
> from the median -1. 
> 
> How can move the normal distribution? 

1) You don't have to move the normal distribution, it
is already centered around the mean:

*---------- begin example ---------
drop _all
set obs 1000
gen x = exp(invnormal(uniform()))
sum x 
replace x = (x-r(mean))/r(sd)
hist x, norm
*----------- end example -----------

2) Comparing the hight of the histrogram bars to a 
curve is a bad way of finding patterns in the 
deviations from the Gaussian distribution. 
Alternatives are Nick Cox's -dpplot- and mine 
-hangroot-. See: -ssc desc dpplot- and 
-ssc desc hangroot-.

Hope this helps,
Maarten

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

visiting address:
Buitenveldertselaan 3 (Metropolitan), room Z434

+31 20 5986715

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


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