When one of the two groups has only one member and the other one more than 49, wilcox.test will exit with the below error message,
n=51; wilcox.test(1:n ~ 1:n==1, conf.int=TRUE) Error in uniroot(wdiff, c(mumin, mumax), tol = 1e-04, zq = qnorm(alpha/2, : f() values at end points not of opposite sign whereas with n=50 a result is returned: n=50; wilcox.test(1:n ~ 1:n==1, conf.int=TRUE) Wilcoxon rank sum test data: 1:n by 1:n == 1 W = 49, p-value = 0.04 alternative hypothesis: true location shift is not equal to 0 95 percent confidence interval: 1 49 sample estimates: difference in location 25 I wonder whether it would be worthwhile to make the wilcox.test function handle such (admittedly pathologic) cases more gracefully. Happy New Year to all - Wolfgang ------------------------------------------------------------------ Wolfgang Huber EBI/EMBL Cambridge UK http://www.ebi.ac.uk/huber ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel