Re: [Phys-l] sample variance versus population variance

["Krishna Chowdary" <professor.head@gmail.com>]

On 10/9/06, John Denker <jsd@av8n.com> wrote:
> On 10/09/2006 05:25 PM, Krishna Chowdary wrote:
>
> Are we talking about the sample variance versus population variance?
> If so, the fix is simple:  replace N by N-1 in the normalization.
> That allows you to convert the sample variance into an unbiased predictor
> of the population variance.
>
>   http://mathworld.wolfram.com/SampleVariance.html
>
> But perhaps I have misunderstood the question.  The generally-used
> notation
> is so messed up that all sorts of inconsistencies can arise.



Thanks for your response, John.  I don't think that's the question I was
asking.  I tried to ask my question more explicitly in the rest of the
message you refer to, and tried to define my notation.  Please let me know
what I might need to clarify or restate.

My question is not about sample variance vs. population variance.  In a
nutshell, it is about whether the standard deviation or the standard
deviation of the mean (of a data set consisting of time measurements) should
be used when propogating uncertainty through a calculation.


--
regards
-Krishna

Krishna Chowdary
Department of Physics & Astronomy
Bucknell University