Had the exact same question. According to this post and Wilcox (p166) you shouldn't calculate Z and Cohen's D respectively because their calculation is based on the normality assumption.

Wilcox provides robust alternatives to Cohen's D (p166-170) including R code in his book. Got the book from my library. It is also available as e-book in both library networks I have access to.

http://store.elsevier.com/Introduction-to-Robust-Estimation-and-Hypothesis-Testing/Rand-Wilcox/isbn-9780123870155/

There are a couple of other posts in this forum asking very similar questions (effect size for Wilcoxon, one sample Wilxocon or Mann-Whitney-U tests just to name a few). You might like to look at those too.

Had the exact same question. According to this post and Wilcox (p166) you shouldn't calculate Z and Cohen's D respectively because their calculation is based on the normality assumption.

Wilcox provides robust alternatives to Cohen's D (p166-170) including R code in his book. Got the book from my library. It is also available as e-book in both library networks I have access to.

http://store.elsevier.com/Introduction-to-Robust-Estimation-and-Hypothesis-Testing/Rand-Wilcox/isbn-9780123870155/

There are a couple of other posts in this forum asking very similar questions (effect size for Wilcoxon, one sample Wilxocon or Mann-Whitney-U tests just to name a few). You might like to look at those too.

Had the exact same question. According to this post and Wilcoxon (p166) you shouldn't calculate Z and Cohen's D respectively because their calculation is based on the normality assumption.

Wilcoxon provides robust alternatives to Cohen's D (p166-170) including R code in his book. Got the book from my library. It is also available as e-book in both library networks I have access to.

http://store.elsevier.com/Introduction-to-Robust-Estimation-and-Hypothesis-Testing/Rand-Wilcox/isbn-9780123870155/

There are a couple of other posts in this forum asking very similar questions (effect size for Wilcoxon, one sample Wilxocon or Mann-Whitney-U tests just to name a few). You might like to look at those too.

Had the exact same question. According to this post and Wilcox (p166) you shouldn't calculate Z and Cohen's D respectively because their calculation is based on the normality assumption.

Wilcox provides robust alternatives to Cohen's D (p166-170) including R code in his book. Got the book from my library. It is also available as e-book in both library networks I have access to.

http://store.elsevier.com/Introduction-to-Robust-Estimation-and-Hypothesis-Testing/Rand-Wilcox/isbn-9780123870155/

There are a couple of other posts in this forum asking very similar questions (effect size for Wilcoxon, one sample Wilxocon or Mann-Whitney-U tests just to name a few). You might like to look at those too.