Talk:Rank correlation

Example please
I don't understand what this is all about. Thanks. 205.228.73.12 11:27, 3 October 2007 (UTC)
 * I agree that a lack of an example makes the content difficult to understand. I have added a new section on a rank correlation measure known as the rank-biserial correlation.  I also worked through an example, so perhaps this will be easier to understand than the earlier sections.  --Friend of facts2 (talk) 17:18, 8 October 2015 (UTC)

When?
Are there situations where Spearman's &rho; is more suitabke than Kendall's &tau;, or vice-versa? How can we choose which one to use? I have no clue about it, but it would be useful to know that. Calimo (talk) 13:18, 23 January 2009 (UTC)
 * I agree. It is useless to list two options if no information is supplied allowing to somehow distinguish them at a glance without clicking individually each one and see for each one an explanation ignoring the other. 212.198.146.203 (talk) 06:47, 30 March 2009 (UTC)

Kendall (1944) reference
The reference Kendall (1944) in the beginning of section Rank_correlation is unavailable. Sieste (talk) 15:53, 25 January 2016 (UTC)

General Correlation Coefficient, notation
It would be much clearer, here and below, if the notation specified that when a sum iterates over $$i$$ and $$j$$, we exclude the elements where $$i=j$$. Perhaps


 * $$\sum_{i, j=1;i \neq j}^{n}{a_{ij} b_{ij}}$$

(although it would be nicer if the lower limits were stacked on two lines).

(I haven't addressed this, though I have made a few smaller changes for clarity.)

Eac2222 (talk) 14:25, 1 August 2016 (UTC)

Proof in the case of Kendall's τ
I believe an expert should look at this. The proof may be missing information, or incorrect.

If we have $$a_{ij} = \sgn(r_j-r_i)$$, then don't we also need to define $$s_i$$ as the rank of the $$i$$th member according to the $$y$$-quality, and define $$b_{ij} = \sgn(s_j-s_i)$$?

(I haven't addressed this, though I have made a few smaller changes for clarity.)

Eac2222 (talk) 14:25, 1 August 2016 (UTC)

Diaconis source
Group Representations in Probability and Statistics by Diaconis was much later than his 1977 paper with Graham Spearman's Footrule as a measure of disarray. I think it should be cited in the section that mentions viewing permutations as a metric space. BlockusYellow (talk) 09:33, 20 October 2023 (UTC)