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Talk:Variance

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Should it be $\operatorname{Var}X$ or $\operatorname{D}X$ ? Moreover I think that $\xi$, $\zeta$ is more appropriate for random variables then $X$, $Y$. What do you think? --Nikita2 (talk)

Yes, $\operatorname{Var}X$, as noted in the "Comments". About $\xi$, $\zeta$ I am neutral; also $X$, $Y$ are OK with me. --Boris Tsirelson (talk) 08:55, 23 February 2013 (CET)

What about mathematical expectation symbol? How should we type it? I found this $\mathbb{E}$ but I think is should be like E. --Nikita2 (talk) 06:01, 25 February 2013 (CET)

Yes, E ($\mathsf{E}$, $\mathrm{E}$, $E$) are widely used. Also $\mathbb{E}$ is used. --Boris Tsirelson (talk) 07:44, 25 February 2013 (CET)
As far as I understand, Ulf (our chief editor) does not try to enforce a uniform style on all our editors.
However, here is what we can do. Put near the beginning of the article something like
$\newcommand{\Ex}{\mathsf{E}}$
and then write $ a = \Ex(X) $ etc. (Look at my wikitext in the edit mode to see what I mean.) This way it will be easy to replace all expectation symbols at once if one will want to do so in a future. --Boris Tsirelson (talk) 08:12, 25 February 2013 (CET)
How to Cite This Entry:
Variance. Encyclopedia of Mathematics. URL: http://www.encyclopediaofmath.org/index.php?title=Variance&oldid=29486