Talk:Fisher's exact test

message: I believe the second a+b should be c+d.109.65.36.159 (talk) 22:01, 13 January 2019 (UTC)
thread_title:  Typo in formula explanation 

message: Mehta, C. R.& Patel, N. R. 1997. Exact inference in categorical data. Biometrics, 53(1), 112-117. definitely does not exist. Is the intention to reference Mehta CR. Exact inference for categorical data. Encyclopedia of Biostatistics 1998; 2:1411–1422 as per? I would probably cite this as . Anyway, I have removed the reference for now, as it was superfluous to the 1984 reference. RupertMillard (Talk) 10:47, 24 March 2009 (UTC)
replies: text: Very odd.  That reference was added by an anon in April 2008, presumably relying on a secondary source.  seglea (talk) 23:43, 24 March 2009 (UTC)
thread_title:  Reference does not exist - Exact inference in categorical data. Biometrics, 53(1), 112-117.' 

message: Can someone spell out how the value from Fisher exact is used please? Is fisher exact value same as p-value? What is considered to be statistically significant?  —Preceding unsigned comment added by Sedoc (talk • contribs) 16:09, 5 June 2009 (UTC)
replies: text: You should try the mathematics reference desk for a question like that.  Baccyak4H (Yak!) 17:41, 5 June 2009 (UTC)
thread_title:  Question 

message: The example
                          	   Men   	  Women  	Row total
Studying                  	1                            	9                  	10
  Not-studying  	11                           	3                  	14
Column total              	12                           	12                 	24
is conveniently analyzed by computing the mean values and variances of the hypergeometric distributions, rather than computing the hypergeometric probabilities themselves.
Based on the sums
                          	   Men   	  Women  	Row total
Studying                  	                             	                   	10
  Not-studying  	                             	                   	14
Column total              	12                           	12                 	24
The mean values are (10)(12)/(24) etc
                          	   Men   	  Women  	Row total
Studying                  	5                            	5                  	10
  Not-studying  	7                            	7                  	14
Column total              	12                           	12                 	24
All the variances are equal to (10)(14)(12)(12)/(24)(24)(24-1)=35/23
The squares of the deviations from the mean values are
all equal to 16.
As 16/(35/23) ≈ 10.5 the difference of proportion is indeed significant.
This calculation is simpler than that in the text.
Bo Jacoby (talk) 05:28, 10 November 2018 (UTC)
thread_title:  Simplification 

message: In Fisher's original example quoted in the article, the number of cups of tea Bristol judged to have had milk put in first is not fixed a priori.  It is of course fixed once the experiment has been carried out, but if we take this as the meaning of 'fixed' then every experiment seems to me to have fixed margins, rendering such a stipulation redundant. Therefore, I am assuming the article currently means to say that both margins must be a prior fixed in order for the test to apply.  It appears to me from Fisher's motivating example that this is in fact untrue. I was wondering if there was disagreement on this point.  If not, I would propose removing the stipulation that marginal totals be fixed. Marko1973 (talk) 16:24, 5 March 2020 (UTC)
replies: text:  Marko1973 makes a perceptive observation.  I would also add that it is not clear whether Bristol was constrained to select exactly 4 and 4.  Presumably she was offered the cups one by one and had to make an irrevocable judgement.  What if she was up to 4-3 (that is, she has said 4 with milk first and 3 with milk second) and, tasting cup number 8 was sure that this had milk first?  Could she say that the final cup was milk first, giving a 5-3 split of her guesses?   I've never been sure about this. Best wishes, Robinh (talk) 20:58, 7 March 2020 (UTC)
thread_title:  On the requirement that the margin of the tables be fixed