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From "Brent Worden" <br...@worden.org>
Subject RE: [math] Only sample variances?
Date Mon, 16 Aug 2004 01:39:39 GMT
Any objection to tracking these and future feature requests using the wiki?
A wish list, if you will.

-----Original Message-----
From: Phil Steitz [mailto:phil@steitz.com]
Sent: Sunday, August 15, 2004 1:06 PM
To: Jakarta Commons Developers List
Subject: Re: [math] Only sample variances?


Kim van der Linde wrote:
> Hi,
>
> I just looked through the variance class, and saw that
> it only supports sample vasriance (N-1) but not
> population variances (N). Any reason for this, and can
> it be added?

It would probably be better to add this to one of the aggregates or
StatUtils or to add a new statistic altother. This is because a
UnivariateStatistic can only report one value. The most commonly used (at
least in statistical applications) value for Variance and Standard
Deviation is the sample statistic, which is why that is what the
statistics named "StandardDeviation" and "Variance" report. From a user's
perspective, its not too hard to convert; but I agree that it would be
convenient to add these. Probably best to make new statistics in the
moment subpackage called "PopulationXxx".  Patches welcome ;-)

Phil


>
> Cheers,
>
> Kim
>
>
>
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