From: Thomas Lumley <tlumley_at_u.washington.edu>

Date: Tue 20 Dec 2005 - 16:18:34 GMT

https://stat.ethz.ch/mailman/listinfo/r-devel Received on Wed Dec 21 03:55:11 2005

Date: Tue 20 Dec 2005 - 16:18:34 GMT

This is the same as PR#8265, which was reported two months ago by someone else from syd.odn.ne.jp. It still isn't a bug. According to Brian Ripley's response at that time, "almost all" the sources he checked gave the correction that R uses.

-thomas

On Tue, 20 Dec 2005, cig69410@syd.odn.ne.jp wrote:

> Full_Name: nobody

*> Version: 2.2.0
**> OS: any
**> Submission from: (NULL) (219.66.34.183)
**>
**>
**> 2 x 2 table, such as
**>
**>> x
**> [,1] [,2]
**> [1,] 10 12
**> [2,] 11 13
**>
**>> chisq.test(x)
**>
**> Pearson's Chi-squared test with Yates'
**> continuity correction
**>
**> data: x
**> X-squared = 0.0732, df = 1, p-value = 0.7868
**>
**> but, X-squared = 0.0732 is over corrected.
**>
**> when abs(a*d-b*c) <= sum(a,b,c,d), chisq.value must be 0!, and P-value must be
**> 1!
**>
**> code of chisq.test must be as follows
**>
**> # if (correct && nrow(x) == 2 && ncol(x) == 2) {
**> # YATES <- 0.5
**> # METHOD <- paste(METHOD, "with Yates' continuity correction")
**> # }
**> # else YATES <- 0
**> # STATISTIC <- sum((abs(x - E) - YATES)^2/E)
**> ## replace begin
**> if (correct && nrow(x) == 2 && ncol(x) == 2) {
**> STATISTIC <- if (abs(x[1,1]*x[2,2]-x[1,2]*x[2,1]) < sum(x)/2) 0
**>
**> else sum((abs(x - E) - 0.5)^2/E)
**> METHOD <- paste(METHOD, "with Yates' continuity correction")
**> }
**> else STATISTIC <- sum((abs(x - E))^2/E)
**> ## replace end
**>
**> ______________________________________________
**> R-devel@r-project.org mailing list
**> https://stat.ethz.ch/mailman/listinfo/r-devel
**>
*

Thomas Lumley Assoc. Professor, Biostatistics tlumley@u.washington.edu University of Washington, Seattle ______________________________________________R-devel@r-project.org mailing list

https://stat.ethz.ch/mailman/listinfo/r-devel Received on Wed Dec 21 03:55:11 2005

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