Talk:Contingency table

Bivariate tables

Please add redirect from here from bivariate tables. ~~ —Preceding unsigned comment added by 139.135.197.201 (talk) 05:06, 8 May 2008 (UTC)

Why? Which direction? They seem entirely different ideas. Contigency tables always contain counts and there are specific statistc rtechniques relating to these, while a "bivariate tables" is much more general ... for example a usual form of presenting tables of the F-distribution is in the form of a bivariate table , with the two degrees of freedom used to enter the table. Thus some contigency tables (the 2D ones) may be special cases of bivariate tables, and vice versa. Without seeing what might go intobivariate tables even the question of links in one or both directions should be left open for now. Melcombe (talk) 09:16, 8 May 2008 (UTC)

(Note: I created a redirect from bivariate table before Melcombe's reply above, but couldn't leave a note then due to connection problems.) I don't see the harm in a redirect myself. For at least one meaning, bivariate tables are a special case of contigency tables, and providing the redirect will help the reader. Yes, it would be better to have an article on bivariate tables, or perhaps on statistical tables, that covers all the different meanings, but the redirect will be some use in the meantime. -- Avenue (talk) 18:00, 8 May 2008 (UTC)

Example is great

..but it would be nice to see a bit more, about expansion beyond two variables, and how the table relates to measures of association. Theblindsage (talk) 08:49, 26 November 2013 (UTC)

Does not describe testing for homogeneity or independence

I looked here because I wanted to reference this page to show someone that you could use $2\times n$ tables in testing whether proportion differed in a number of different trials (say we toss 10 coins and record the numbers of heads and tails for each, and we want to test whether the heads probabilities differ). But the presentation here does not hint that the table might be used for that -- it is solely concerned with the table as a summary of covariation of two variables. Felsenst (talk) 17:48, 24 October 2008 (UTC)

Tests of independence & homogeneity: I think it would make sense to expand or modify the section "Standard contents of a contingency table" (or add a new section) to discuss Pearson's chi-squared (and Yates's correction) and Fisher's exact test for independence. The example given (male/female vs left/right hand) is perfect for demonstrating 2x2 contingency table and Pearson chi-squared, Yates's correction, Fisher exact test, phi and other coefficients of association. (For on-line calculator see http://vassarstats.net/tab2x2.html or https://www.socscistatistics.com/tests/chisquare/Default2.aspx or https://www.socscistatistics.com/tests/fisher/Default2.aspx) Tbrill 013 (talk) 16:07, 26 October 2018 (UTC)

Quality of writing

Needs to be completely rewritten. Lots of random information and jargon tossed about. — Preceding unsigned comment added by 138.88.98.187 (talk) 02:40, 16 February 2012 (UTC)

The range of $\phi$

I think that $\phi$ varies from 0 to 1 (can not have negative values). Because both $\chi ^{2}$ and $N$ have positive values.

--CogitoErgoSum.AgeRemigo (talk) 04:47, 12 May 2012 (UTC)

The phi coefficient can have negative values. It cannot, however, be less than -1.Iss246 (talk) 15:27, 12 May 2012 (UTC)

The confusion here is the use of the principal square root radical when it should be preceded by ± . The article Phi coefficient, which initially expresses the square of phi to avoid this issue, then gives information on how to get a signed phi. I'll fix this article to get rid of the wrong assertion that the principal square root of a positive number can be negative. Loraof (talk) 17:25, 4 August 2017 (UTC)

Contingency table vs confusion matrix

What is the difference between a contingency table and a confusion matrix? Do both terms refer to the same thing? If so, perhaps a merge should be considered. pgr94 (talk) 11:35, 13 June 2013 (UTC)

I get the impression that a confusion matrix is a special kind of contingency table, where the same set of values (often just false and true) appears in columns and rows (rows for real values, columns for observed values), but I don't think they should be... confused. -- RFST (talk) 06:38, 28 March 2016 (UTC)

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Uncertainty coefficient range

Here, the range of the uncertainty coefficient is reported here as [-1,1], yet the main uncertainty coefficient article lists that the range is [0,1]. Either or both articles should be updated.

Problem with the formula for the adjusted contingency coefficient

The article says:

"C can be adjusted so it reaches a maximum of 1.0 when there is complete association in a table of any number of rows and columns by dividing C by ${\sqrt {\frac {k-1}{k}}}$ where k is the number of rows or columns, when the table is square [...]"

It apparently relies on Blaikie, N. (2003) Analyzing Quantitative Data. Sage: Thousand Oaks, CA. p. 100. I can't check as I don't have this book, but I trust the person who added the info.

The problem is that this other reference (2010) says that for this formula, "k = the number of rows or columns, whichever is smaller", which is contradictory with "when the table is square" as stated by the previous reference.

I'm not a mathematician and unable to tell which of these two sources is right. Has anybody some information that could clarify the apparent contradiction?

By the way, the ${\sqrt {\frac {k-1}{k}}}$ correction should be attributed to James Sakoda.

Thanks, 77.206.169.95 (talk) 10:15, 30 June 2020 (UTC)