# Talk:Divergence (statistics)

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## positive definiteness in the definition

The third property of divergence is given in the text as,

The matrix g(D) (see definition in the “geometrical properties” section) is strictly positive-definite everywhere on S.

I haven't read the reference yet, but it doesn't seem necessary to put it in the definition. At least, a good explanation is required here. --Memming (talk) 18:13, 29 January 2010 (UTC)

## Notation

The notation used, while appreciably terse, is also cryptic and unapproachable. This should be revised, either to further enhance its readability or it should link to a page that helps to disambiguate the meaning of the notation used. — Preceding unsigned comment added by 132.3.57.68 (talk) 22:52, 9 March 2012 (UTC)

## Merger proposal

I propose that Statistical distance be merged into Divergence (statistics). It seems to me that a statistical distance, when it refers to comparison of two distributions, merely satisfies a somewhat tighter definition than what is required from a divergence. Currently the two articles give conflicting definitions of a distance, and this could be clarified by discussing them in a common framework. I think it would be okay to also explain comparison of a point to a distribution within the article Divergence (statistics), leaving no need for a Statistical distance article, except for as a redirect. Olli Niemitalo (talk) 10:33, 4 December 2014 (UTC)

Closing, as no support over 2.5 years. Klbrain (talk) 20:05, 15 August 2017 (UTC)

## || Notation

What is the origin of the || notation used in this article? Divergences and distance measures in statistics are traditionally written D(P,Q) or similar rather than D(P||Q). While the || notation is not completely unknown in the statistics research literature, it is very rare. The || notation is not used in any of the cited references, nor in the Wikipedia page on statistical distance, nor does it agree with the definition of || in the Wikipedia page List of mathematical symbols. I suggest reverting to historical notation, which is simpler and more widely understood. GKSmyth (talk) 10:18, 28 May 2015 (UTC)