Comments on: Friedman Test in R https://www.datanovia.com/en/lessons/friedman-test-in-r/ Data Mining and Statistics for Decision Support Mon, 19 Jun 2023 14:06:45 +0000 hourly 1 https://wordpress.org/?v=6.8.2 By: Karen Butina https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-28801 Mon, 19 Jun 2023 14:06:45 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-28801 Hi! Thank you so much for the tutorial 🙂
I have understood that several people recommend Dunn’s posthoc test for pairwise comparisons. What was your rationale for choosing Wilcoxon signed-rank?

]]> By: Andrii https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-28588 Tue, 03 Jan 2023 17:41:47 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-28588 In reply to kassambara.

Hello,

Actually, the solutions presented in the MSalena’s link (i.e., class type as factor NOR a “better” ordering NOR change the dataframe into matrix NOR the presences of NAs) do not solve the problem of “unreplicated complete block design”.

Essentially, the issue is that unreplicated complete block design means that each subject has ONLY 1 observation per each experimental condition.

Therefore, if you have several observations per each experimental condition, you must get a central tendency first (mean or median).

I myself have 15 observations per 3 experimental conditions (hence 5 observations per each condition). When I try to perform the Friedman test on my “raw” data, I get the error message of unreplicated complete block design. But when I average the five values, the error disappears.

Hope this helps someone in the future.

@Kassambara, please correct me if I am wrong and thanks for creating such a useful website!

Cheers,
Andrii

]]> By: Laura https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-23022 Wed, 28 Sep 2022 11:31:32 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-23022 Hi, thanks for this helfpul tutorial. It was working perfectly for me until I recently updated my R to version 4.0.5, and reinstalled the packages. Now, when I run the friedmans test, I get the error: Error in UseMethod(“friedman_test”) :
no applicable method for ‘friedman_test’ applied to an object of class “data.frame”. Do you know how to resolve this issue? Many thanks, Laura

]]> By: Leander https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-22808 Fri, 13 May 2022 09:33:47 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-22808 Hey. Great tutorial!
I am comparing five groups with the Wilcoxon test and have quite many significant differences, so the plot looks very messy.
Is there a way to visualize the pairwise comparison results using the lettering with your approach?

]]> By: Olaniyi Sonubi https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-22027 Sat, 22 May 2021 01:46:53 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-22027 Why is Nemenyi Post-hoc Test not done or is the Wilcoxon signed rank test a substitute to that

]]> By: Emilia https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-22014 Sun, 16 May 2021 19:00:08 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-22014 Hi, do you know why when I do the box plot with the p-values I get Error in.valide_y_position (y.position, data):
can’t find the y.position variable ‘y.position’ in the data??

]]> By: kassambara https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-20622 Sun, 21 Jun 2020 19:35:16 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-20622 In reply to Lu.

Please make sure you have installed the latest version of the rstatix package

]]> By: Lu https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-20621 Sun, 21 Jun 2020 13:47:13 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-20621 Thank you for the amazing tutorials!
Unfortunately I am stuck with the visualisation: when entering
pwc % add_xy_position(x = “time”)

I get the following error:
Error: `x` must be a vector, not a `tbl_df/tbl/data.frame/rstatix_test/wilcox_test` object.

]]> By: kassambara https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-20503 Fri, 05 Jun 2020 22:47:52 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-20503 In reply to MSalena.

Thank you for your input, appreciated!

]]> By: MSalena https://www.datanovia.com/en/lessons/friedman-test-in-r/#comment-20502 Fri, 05 Jun 2020 21:06:54 +0000 https://www.datanovia.com/en/?post_type=dt_lessons&p=10890#comment-20502 This issue has been resolved at Friedman test unreplicated complete block design error

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