Talk:Phi coefficient

Clarification requested

Hello page author:

I am not clear on what is meant by "If both have a 50/50 split, the range of phi will range from −1 to +1." Can you elaborate?

I have looked at the reference by Davenport El-Sanhury (1991), and tested values in a spreadsheet, but I am still none the wiser. When I calculate Phi in the spreadsheet and compare it to the correl() function, the two methods agree.

I was wanting to see if I could use Pearson's correlation coefficient (r) on binary (1,0) data.

Best wishes, Vstrom650 (talk) 16:20, 8 July 2010 (UTC) J.

Is the formula correct?

The formula says : $\phi ={\sqrt {\frac {\chi ^{2}}{n}}}$, but I think that's true only up to sign, since phi can be negative. 109.67.6.27 (talk) 11:35, 20 January 2020 (UTC)

How can phi be negative? It is based on chi-square which is always non-negative. Tal Galili (talk) 12:27, 20 January 2020 (UTC)

Further question: how many degrees of freedom belong to the chi-squared variable? Surakmath (talk) 23:16, 21 February 2022 (UTC)

Inaccurate citation?

I can't find where the source cited for the following claim makes any mention of phi: "Phi is related to the point-biserial correlation coefficient and Cohen's d and estimates the extent of the relationship between two variables (2×2).[4]" [4] Aaron, B., Kromrey, J. D., & Ferron, J. M. (1998, November). Equating r-based and d-based effect-size indices: Problems with a commonly recommended formula. Paper presented at the annual meeting of the Florida Educational Research Association, Orlando, FL. (ERIC Document Reproduction Service No. ED433353) https://eric.ed.gov/?id=ED433353 Shedsan (talk) 01:56, 9 March 2020 (UTC)

Proposed changes to transcluded formula template

Fellow Wikipedians: I've proposed some changes to the formula infobox transcluded into this article, with the goal of trimming down its overpowering (if not excessive) width. My original message with some explanatory notes is at Template talk:Confusion matrix terms#Template_width, and you can see the revised template layout I've proposed by viewing its sandbox version.

There have been no responses over there in well over two months, and since the changes I'm proposing are significant enough to possibly be contentious, I wanted to invite any interested Wikipedians to discuss them over at the template's talk page. Thanks! FeRDNYC (talk) 00:03, 5 January 2022 (UTC)

Removed content

I have removed a large section of this article because there was a long history of apparent inappropriate self citing (see here). It may merit some mention in the article, but it seemed overly detailed and part of an academic dispute which should not be trying to be settled on Wikipedia. SmartSE (talk) 15:29, 30 January 2026 (UTC)