The function 'pchisq' from the 'stats' library gives a wrong result if the argument equals exactly zero:
# Upper tail of central 1-df chi^2 distribution > pchisq(1 , 1, ncp=0, lower.tail = F, log.p = FALSE) [1] 0.3173105 > pchisq(0.5 , 1, ncp=0, lower.tail = F, log.p = FALSE) [1] 0.4795001 > pchisq(0.01 , 1, ncp=0, lower.tail = F, log.p = FALSE) [1] 0.9203443 > pchisq(0.0001 , 1, ncp=0, lower.tail = F, log.p = FALSE) [1] 0.9920213 > pchisq(0.00000001, 1, ncp=0, lower.tail = F, log.p = FALSE) [1] 0.9999202 > pchisq(0.00 , 1, ncp=0, lower.tail = F, log.p = FALSE) [1] 0 ## Should be 1.0 The error occurred with R version 2.4.0 (windows) and version 2.3.1 (linux). Best regards, Michael Nothnagel --- Dr. Michael Nothnagel Institute of Medical Informatics and Statistics, University of Kiel http://capella.uni-kiel.de/ --- ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
