On Tue, 2003-12-09 at 02:23, Torsten Hothorn wrote: > > Hello everybody, > > > > I'm seeing some strange behavior on R 1.8.1 on Intel/Linux compiled > > with gcc 3.2.2. The p-value calculated from the chisq.test function is > > incorrect for some input values: > > > > > > > chisq.test(matrix(c(0, 1, 1, 12555), 2, 2), simulate.p.value=TRUE) > > > > Pearson's Chi-squared test with simulated p-value (based on 2000 > > replicates) > > > > data: matrix(c(0, 1, 1, 12555), 2, 2) > > X-squared = 1e-04, df = NA, p-value = 1 > > > > > chisq.test(matrix(c(0, 1, 1, 12556), 2, 2), simulate.p.value=TRUE) > > [...] > > data: matrix(c(0, 1, 1, 12556), 2, 2) > > X-squared = 1e-04, df = NA, p-value = < 2.2e-16 > > > > > chisq.test(matrix(c(0, 1, 1, 12557), 2, 2), simulate.p.value=TRUE) > > [...] > > data: matrix(c(0, 1, 1, 12557), 2, 2) > > X-squared = 1e-04, df = NA, p-value = 1 > > > > this does not happen with R-1.8.1 and gcc 2.95.4 on Debian stable: > > R> chisq.test(matrix(c(0, 1, 1, 12555), 2, 2), > simulate.p.value=TRUE)$p.value > [1] 1 > R> chisq.test(matrix(c(0, 1, 1, 12556), 2, 2), > simulate.p.value=TRUE)$p.value > [1] 1 > R> chisq.test(matrix(c(0, 1, 1, 12557), 2, 2), > simulate.p.value=TRUE)$p.value > [1] 1 > > neither with R-1.9.0 (unstable). Is this reproducible without using > `set.seed' on your system? > > Best, > > Torsten
<snip> Confirmed on Fedora Core 1 with R Version 1.8.1 Patched (2003-12-07) compiled using "gcc (GCC) 3.3.2 20031107 (Red Hat Linux 3.3.2-2)". > chisq.test(matrix(c(0, 1, 1, 12555), 2, 2), simulate.p.value=TRUE) ... X-squared = 1e-04, df = NA, p-value = 1 > chisq.test(matrix(c(0, 1, 1, 12556), 2, 2), simulate.p.value=TRUE) X-squared = 1e-04, df = NA, p-value = < 2.2e-16 ... > chisq.test(matrix(c(0, 1, 1, 12557), 2, 2), simulate.p.value=TRUE) ... X-squared = 1e-04, df = NA, p-value = 1 HTH, Marc Schwartz ______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help