Re: Determining if samples are normal

[Robert A. Macy]

Right!  

checked empirically using x=rand(1,1000) and hist(x) 
it's there all right.  

Didn't make sense at first then I remembered
.5 + .5 done four different ways only reinforces the
average, but...

+0 +1
+0 0
1 0
or,
1 1

rarely enhances the edges but definitely moves the
weighting towards the average.  

Learn something everyday.  


So what is the PDF if the two are multiplied?

              - Robert -
 



On Mon, 26 Sep 2005 14:36:30 -0400 (EDT)
 Przemek Klosowski <address@hidden> wrote:
>    Sorry, to jump in where I have very little knowledge
> and
>    understanding, but doesn't the sum preserve the
>    distribution?  Seems counter intuitive to have the sum
>    change the distribution if it's identical.  Isn't it
>    multiply that makes it triangular?
> 
> No, check for yourself by doing
> hist(rand(1e5,1)+rand(1e5,1),100).
> Read
> http://en.wikipedia.org/wiki/Probability_distributions:
> "The
> probability distribution of the sum of two random
> variables is the
> convolution of each of their distributions."



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