I have results from the same test applied to two independent samples: x <- c(17, 12, 13, 16, 9, 19, 21, 12, 18, 17) y <- c(10, 6, 15, 9, 8, 11, 8, 16, 13, 7, 5, 14) And I want to compute a Wilcoxon rank sum test. When I calculate the statistic *T<sub>W</sub>* by hand, I get: *T<sub>W</sub>* = ∑ *rank* ( *X<sub>i</sub>* ) = 156.5 When I let R perform a `wilcox.test(x, y, correct = F)`, I get: W = 101.5 Why is that? Shouldn't the statistic *W* only be returned when I perform a *signed* rank test with `paired = T`? Or do I misunderstand the rank sum test? **How can I tell R to output T<sub>W</sub>?** * * * As part of the test results, not through something like: dat <- data.frame(v = c(x, y), s = factor(rep(c("x", "y"), c(10, 12)))) dat$r <- rank(dat$v) T.W <- sum(dat$r[dat$s == "x"])