Testing the Assumptions for the Wilcoxon Signed-Rank Test in SPSS

This video demonstrates how to test the assumptions for a Wilcoxon Signed-Rank test using SPSS, including the assumption of symmetrical distribution. The Wilcoxon Signed-Rank test is a nonparametric alternative to the dependent-samples t test (paired-samples t test).

[@garr2991]

What happens if my difference distribution is non-symmetrical on the boxplot?

[@angelinastanton7996]

After watching this video, the Wilcoxon Signed Rank Test was easier for me to understand when reading the results. It was helpful to be walked through reading the ranks and test statistics. This is a great alternative for determining the differences between pretest and posttest, especially if you do not have a normal distribution of data.

[@amandagerrick5407]

This video was helpful in better understanding symmetrical distribution within a data set using the Wilcoxon Signed-Rank test. I like being able to see the results as differences between the pretest and posttest.

[@angelinastanton7996]

I also like seeing the results as differences between the pretest and posttest, everything seems to make more sense to me afterwards.

[@sarahjones208]

Thank you for making this video, it helps clarify some confusing concepts.

[@angelinastanton7996]

The video definitely helped me understand what the purpose of the Wilcoxon Signed Rank test is for and how to interpret the results.

[@virginiamurrey9139]

This video has provided me with new information, that would be very useful for future research. I will continually remember to use all of the videos as references to assist me in increasing my knowledge, and using for future projects.

[@elnazabaie3965]

it was very helpful thank you so much

[@chewengsun2902]

Thanks for the very helpful and clear video to determine whether there is a significant difference between pretest and posttest scores (probably caused by an intervention or treatment). It also shows that while one test score distribution is normally distributed (parametric) and the other non-parametric, the difference between them can be used to test for symmetry and hence the Wilcoxon signed rank test.

[@joseliz8762]

thank you for sharing this video. i found it informative and useful should i do research and come to the need to use this

[@khanhphuvang]

Thanks for useful video. But, if the data violated the symmetry assumption. What will we do next? please.

[@stuartsemujju8565]

You can also look at the vargha delaney effect size to show the significance in statistical difference

[@thehealthanddiseaseblog3620]

That is exactly my question. What if the difference is not symmetrical?

[@colourfulchaos]

@@thehealthanddiseaseblog3620 Try the Sign Test: statistics.laerd.com/spss-tutorials/sign-test-using-spss-statistics.php

[@ThomasEipeRoshin]

What test should i use to compare the effects of 3 different drugs on variable outcome (both pre and post test)
Groups: "Drug A" "Drug B" "Drug C"
Test: Pretest and Post-test

[@pinkeatspeaches]

Have you found out by any chance?

[@diarmuidodowdhill9824]

@@pinkeatspeaches Adding a filter to your data and completing this process for each drug

[@Tracks777]

Good! Keep it up!

[@DrGrande]

Thank you -

[@tutiagustin645]

Todd Grande
If my data violate the symetry assumption, what method should I use then?
Thanks in advance 🙏

[@sohagsarkar]

Hi, I had a query regarding Wilcoxon signed rank test. Can Wilcoxon signed rank test (non parametric) be applied to compare two variables having different units of measurement (UOM):
Eg:
1. Average mobile data usage per user (having values in buckets like: 0-1 GigaByte per month, 1-2 GigaByte per month; and so on)
vs
2. Average SMS usage per user (having values like 0-10 SMS per month, 10-50 SMS per month, 50-100 SMS per month; and so on).
So test if users who are high data usage are using IP-based messaging like Whatsapp etc. over Mobile operator's SMS?

[@aidakashefi9586]

hi againnn, what does the z-score means, please?