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Re: Puzzled by the "Variance"

• To: mathgroup at smc.vnet.net
• Subject: [mg86548] Re: [mg86506] Puzzled by the "Variance"
• From: Bob Hanlon <hanlonr at cox.net>
• Date: Thu, 13 Mar 2008 04:35:18 -0500 (EST)
• Reply-to: hanlonr at cox.net

As stated in the Help, Variance provides the unbiased estimate (divided by (Length[list] - 1) rather than Length[list]). See 

http : // mathworld.wolfram.com/Variance.html



Bob Hanlon

---- Elements <philyer 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
> 
>