Talk:Covariance and correlation

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Stub question

This page is not really a stub, it is pretty complete and concise explanation of differences between the two concepts. If you edit this page, please do so sparingly. —Preceding unsigned comment added by 137.100.46.254 (talk) 18:31, 14 January 2010 (UTC)[reply]

No doubt there are many reasons why this has been put down as a stub. One of them is the lack of citations, both the relations stated and more importantly for the other statements of supposed "fact". Melcombe (talk) 10:12, 18 January 2010 (UTC)[reply]

How are people supposed to discover this article? It's not linked from either Covariance or Correlation, and those articles don't discuss the relation between both concepts in a prominent place.--88.73.53.132 (talk) 16:14, 1 November 2011 (UTC)[reply]

WTF?

"The covariance of a variable with itself (i.e. X = Y) is called the variance" You can't tell me that sentence makes a damn bit of sense. It also contradicts: http://en.wikipedia.org/wiki/Variance, which says "The variance is a measure of how far a set of numbers is spread out". Theblindsage (talk) 22:34, 27 February 2012 (UTC)[reply]

WTF#2

"The correlation of a variable with itself is always 1" a) How can something correlate with itself? Ah, wait--it is just terrible grammar. "...(except in the degenerate case where the two variances are zero, in which case the correlation does not exist)" b) What is a degenerate case? At least give either an example or a link to what you are talking about. c) How can a variance be zero? d) Correlation does not exist, or is equal to zero? (Very different, those two). Theblindsage (talk) 22:34, 27 February 2012 (UTC)[reply]