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From Phil Steitz <p...@steitz.com>
Subject Re: [math] Only sample variances?
Date Sun, 15 Aug 2004 18:05:45 GMT
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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