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Re: Puzzled by the "Variance"

  • To: mathgroup at smc.vnet.net
  • Subject: [mg86515] Re: [mg86506] Puzzled by the "Variance"
  • From: George Woodrow III <georgevw3 at mac.com>
  • Date: Thu, 13 Mar 2008 04:29:07 -0500 (EST)
  • References: <200803121029.FAA17511@smc.vnet.net>

Variance properly has (n-1) in the denominator, to account for one  
fewer degrees of freedom.

george

On Mar 12, 2008, at 6:29 AM, Elements 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
>
>



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