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RE: Puzzled by the "Variance"

  • To: mathgroup at smc.vnet.net
  • Subject: [mg86576] RE: [mg86506] Puzzled by the "Variance"
  • From: "Jaccard Florian" <Florian.Jaccard at he-arc.ch>
  • Date: Thu, 13 Mar 2008 20:55:04 -0500 (EST)
  • References: <200803121029.FAA17511@smc.vnet.net>

You've got a lot of very good answers...

As a complement:

In earlier versions, you could also ask for the biased (or population) 
variance. It still works with v.6, in spice of the fact that it's 
considered as "removed"...

Just write:

data = {1, 2, 3};
<< "Statistics`"
VarianceMLE[data]

It gives: 2/3

But it's quite dangerous to use "removed" mathematica packages...

I just don't understand why Wolfram removed this function... In most 
other systems, you can ask for both variances!

Florian Jaccard


-----Message d'origine-----
De: Elements [mailto:philyer at gmail.com]
Envoy=E9=A0: mercredi, 12. mars 2008 11:29
=C0=A0: mathgroup at smc.vnet.net
Objet=A0: [mg86506] Puzzled by the "Variance"

Greeting all
I'm puzzled by the function "Variance". We can learn how to calculate
variance from this =
page:http://mathworld.wolfram.com/SampleVariance.html.
For example, calculate the sample variance of {1,2,3}. the average of
{1,2,3} is 2, then the variance should be =
((1-2)^2+(2-2)^2+(3-2)^2)/3=2/3.
But mathematica gives that:

In[10]:= Variance[{1.0,2.0,3.0}]
Out[10]= 1.

Why??
--
Best Wishes!
Yours Sincerely




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