I am currently writing a seminar paper where I among other things conduct a Wilcoxon rank-sum test. The sample size is very small, so I don't have any significant results. My professor thought it might be interesting to calculate the sample size that would be sufficient for a 5%-signifance level assuming the effect is as strong as I found.
I am a little lost since I have never made such a sample-size calculation. I found the R-package "samplesize" with a function called "n.wilcox.ord" that seems to do the trick but unfortunately I can't make any sense of it (especially the "vector of expected proportions" that is needed there).
It's a within subjects design with a sample size of 22. Statistical power is 0.8 with an alpha of 0.05
Is there maybe another way to do the computation? Any help is strongly appreciated!