Imagine I would like to test whether the blood oxygen saturation differs significantly between left and right arm. Now, imagine that:
- All measurements are percentages
- The differences between pairs show positive skewness and bimodality
- The sample size is composed by 50 volunteers (50 left + 50 right = 50 pairs of measurements)
- I have not to assume that the difference is clinically significant (only statistically)
My question is: is the Wilcoxon signed-rank test a good choice to test that, or are percentages not tested well by it?
(I use R)
I read those Q&A, but my doubts are still there mainly because I do not understand if a nonparametric test would be more appropriate and my data would be strictly percentages: Percentages from non binomial data: is ANOVA / Kruskal-Wallis appropriate?, Using ANOVA on percentages? and Wilcoxon signed-rank test for proportion variable response?