Hello,
I use t.test for normal distributed and wilcox.test for non-normal
distributed samples.
It is easy to write a function for t.test that calculates the effect
size, because all parts of the formula are available from the t.test
result: r = sqrt(t*t / (t*t + df))
However, for Wilcoxon tests, the formula for effect sizes is:
r = Z / sqrt(N)
I wonder how I can calculate the Z-score in R for a Wilcoxon test.
BTW, would it be correct to name "wilcox.test(..., paired=F)" a
"Mann-Whitney test" in a report? If I understand the documentation
(?wilcox.test) correctly, R does actually not use Mann-Whitney, but the
equivalent Wilcoxon test.
Thanks for clarification.
Claus