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https://issues.apache.org/jira/browse/ACCUMULO-2494?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=13940922#comment-13940922
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Mike Drob commented on ACCUMULO-2494:
-------------------------------------
re: fix version
The latest version of the patch delegates all calculations in Stat to
commons-math. However, 1.4 does not yet have a dependency on commons-math so I
am hesitant to introduce one. [~busbey] suggested on RB that we apply a known
issue note to 1.4 (presumably javadoc?) and then apply the code change in 1.5
and newer.
[~kturner] - You expressed some concern previously, can you articulate it
further?
> Stat calculation of STDEV may be inaccurate
> -------------------------------------------
>
> Key: ACCUMULO-2494
> URL: https://issues.apache.org/jira/browse/ACCUMULO-2494
> Project: Accumulo
> Issue Type: Bug
> Components: client
> Reporter: Mike Drob
>
> The math is sound, but it is susceptible to rounding errors. We should
> address that.
> See http://www.strchr.com/standard_deviation_in_one_pass and
> http://www.cs.berkeley.edu/~mhoemmen/cs194/Tutorials/variance.pdf
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