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Re: Puzzled by the "Variance"

• To: mathgroup at smc.vnet.net
• Subject: [mg86531] Re: Puzzled by the "Variance"
• From: Januk <ggroup at sarj.ca>
• Date: Thu, 13 Mar 2008 04:32:07 -0500 (EST)
• References: <fr8b97$h2s$1@smc.vnet.net>

You are using equation 1 of that page, Variance uses equation 4.  The
reason for the difference is subtle and is explained in the text
between the two equations.

On Mar 12, 6:28=A0am, Elements <phil... at gmail.com> wrote:
> 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