On Sun, 30 Oct 2005, P Ehlers wrote: > [EMAIL PROTECTED] wrote: >> Full_Name: foo ba baz >> Version: R2.2.0 >> OS: Mac OS X (10.4) >> Submission from: (NULL) (219.66.32.183) >> >> >> chisq.test(matrix(c(9,10,9,11),2,2)) >> >> Chi-square value must be 0, and, P value must be 0 >> R does over correction >> >> when | a d - b c | < n / 2 ，chi-sq must be 0 > > (Presumably, you mean P-value = 1.) > If you don't want the correction, set correct=FALSE. (The > results won't differ much.) > > A better example is > > chisq.test(matrix(c(9,10,9,10),2,2)) > > for which R probably should return X-squared = 0.
R is using the correction that almost all the sources I looked at suggest. You can't go around adjusting X^2 for just some values of the data: the claim is that the adjusted statistic has a more accurate chisq distribution under the null. I think at this remove it does not matter what Yates' suggested (although if I were writing a textbook I would find out), especially as the R documentation does not mention Yates. -- Brian D. Ripley, [EMAIL PROTECTED] Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
