Talk:Algorithms for calculating variance: Difference between revisions

Revision as of 10:17, 24 July 2014

Revision as of 10:25, 24 July 2014

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Is this algorithm right? I'm not an expert, but when I compare it to the online variance computation, it's different, and if I replace y with x, I should get cov(x,x) = var(x), so could anyone have a look please? [[Special:Contributions/131.227.95.222|131.227.95.222]] ([[User talk:131.227.95.222|talk]]) 18:03, 27 February 2013 (UTC)

: Alright, I found a paper talking about this and now I understand that the formula is talking about co-moments and not covariances, I will add the note to the article. [[Special:Contributions/131.227.95.222|131.227.95.222]] ([[User talk:131.227.95.222|talk]]) 10:31, 28 February 2013 (UTC)

== Merge discussion ==

There was a merge tag added at [[Standard deviation#Rapid calculation methods]] to this article. I think it is quite reasonable to have that section be a summary of this article. <s>I must admit I was rather surprised I couldn't find a version of the <math>\operatorname{E}\left[(X-\operatorname{E}(X))^2\right] = \operatorname{E}\left[X^2 \right] - (\operatorname{E}[X])^2</math> formula in the standard deviation article, I've put a bit in its talk page about that and that that article is slow referring to variance and never links to it.</s>

For this article as old speedup calculation method is at [[assumed mean]]. [[User:Dmcq|Dmcq]] ([[User talk:Dmcq|talk]]) 09:19, 17 May 2013 (UTC)

I think what is written here is much more clear than the article that the merge tag refers to. Hence I propose to leave it as is. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/194.105.120.70|194.105.120.70]] ([[User talk:194.105.120.70|talk]]) 14:50, 11 July 2013 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

* '''Oppose merge''' Too big for [[Standard deviation]] article per [[WP:SUMMARYSTYLE]] and qualifies as notable under [[WP:GNG]] per its references. [[User:Brycehughes|Brycehughes]] ([[User talk:Brycehughes|talk]]) 04:41, 9 November 2013 (UTC)

* I think we all agree with {{@|Brycehughes}} that the Algorithms article is too big to merge into the [[Standard deviation]] one. The merge tag suggests a move in the other direction.

* I think the sensible thing is to use Summary Style, as {{@|Dmcq}} suggests. The detailed algorithms article need not change very much, but the section at [[Standard deviation#Rapid calculation methods]] should be rewritten as a summary of the algorithms article.

* --[[User:Hro%C3%B0ulf|Hroðulf]] (or Hrothulf) ([[User talk:Hro%C3%B0ulf|Talk]]) 10:17, 24 July 2014 (UTC)

== Kurtosis algorithm biased for normal distribution? ==

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What makes the first algorithm "naive?" I see no explanation as to how it is lacking, or what rules are broken, or what complications are not taken into consideration. [[User:Edison|Edison]] ([[User talk:Edison|talk]]) 18:11, 26 May 2014 (UTC)

:{{re|Edison}} It is naive because it is the obvious application of the formula that defines variance.

:As for things that are lacking, those are discussed further down the article. For example, it is highly vulnerable to <s>underflow</s>, <ins>[[loss of significance]]</ins>, and it could be more efficient.

:Feel free to edit the article to make these things more clear.

:--[[User:Hro%C3%B0ulf|Hroðulf]] (or Hrothulf) ([[User talk:Hro%C3%B0ulf|Talk]]) 13:27, 23 July 2014 (UTC)

== Merge discussion ==

There was a merge tag added at [[Standard deviation#Rapid calculation methods]] to this article. I think it is quite reasonable to have that section be a summary of this article. <s>I must admit I was rather surprised I couldn't find a version of the <math>\operatorname{E}\left[(X-\operatorname{E}(X))^2\right] = \operatorname{E}\left[X^2 \right] - (\operatorname{E}[X])^2</math> formula in the standard deviation article, I've put a bit in its talk page about that and that that article is slow referring to variance and never links to it.</s>

For this article as old speedup calculation method is at [[assumed mean]]. [[User:Dmcq|Dmcq]] ([[User talk:Dmcq|talk]]) 09:19, 17 May 2013 (UTC)

I think what is written here is much more clear than the article that the merge tag refers to. Hence I propose to leave it as is. <span style="font-size: smaller;" class="autosigned">— Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/194.105.120.70|194.105.120.70]] ([[User talk:194.105.120.70|talk]]) 14:50, 11 July 2013 (UTC)</span><!-- Template:Unsigned IP --> <!--Autosigned by SineBot-->

* '''Oppose merge''' Too big for [[Standard deviation]] article per [[WP:SUMMARYSTYLE]] and qualifies as notable under [[WP:GNG]] per its references. [[User:Brycehughes|Brycehughes]] ([[User talk:Brycehughes|talk]]) 04:41, 9 November 2013 (UTC)

* I think we all agree with {{@re|Brycehughes}} that the Algorithms article is too big to merge into the [[Standard deviation]] one. The merge tag suggests a move in the other direction.

* I think the sensible thing is to use Summary Style, as {{@re|Dmcq}} suggests. The detailed algorithms article need not change very much, but the section at [[Standard deviation#Rapid calculation methods]] should be rewritten as a summary of the algorithms article.

* --[[User:Hro%C3%B0ulf|Hroðulf]] (or Hrothulf) ([[User talk:Hro%C3%B0ulf|Talk]]) 10:17, 24 July 2014 (UTC)