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I have question regarding the Wilcoxon test and if the results can be represented visually.

I had 10 participants in my experiment where by I asked participants to read sentences and then they repeated the sentences (there were three different types of repetitions- analogous to three different treatments) and then a post testing period.

Thus I had Pre_treatment 1 vs. Post treatment_1, Pre_treatment 2 vs. Post treatment_2, Pre_treatment 3 vs. Post treatment_3.

My results were significant but I wasn't sure how to represent the results since using mean won't make sense.

Also, is there any other test I could employ? (I did use a parametric repeated measures ANOVA in first pass but since the sample size was small I didn't think it was appropriate.)

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  • $\begingroup$ Under the assumption of symmetry used by the Wilcoxon test, all location parameters are equivalent, provided of course that they exist. $\endgroup$
    – JohnK
    May 15, 2015 at 14:02

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Boxplots are very useful for visualization of such data:

enter image description here

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The test sounds fine. Check that you meet the assumptions of the test. The most important assumption to check is that the distribution of the differences is symmetric in shape. If that doesn't hold, take a look at the sign test which doesn't have that assumption but isn't as powerful.

For the Wilcoxon signed rank test, I saw this visualization once in a text book. Unfortunately, I've forgotten which one.

enter image description here

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