Hello ,
I'm asking you why they consider that Wilcoxon test and U Mann Whitney test are the same ? Can we use this test to examine 2 numeric variables for independent groups ?
Thank you
Hello Meriem,
You are right that both tests are nonparametric alternatives to the t-test for comparing 2 samples. However, Wilcoxon is designed to deal with DEPENDENT samples by comparing central tendencies of the samples (mean or median). Mann-Whitney-U is designed for INDEPENDENT samples and compares the distribution of your samples.
Best,
Steffen
Dear Steffen,
Thank you for the response. I agree that there are differences between those tests but i don't know why when i mention this command on rstudio tool
??Whitney.test
they redirect me to Wilcoxon Rank Sum and Signed Rank Tests , Description
Performs one- and two-sample Wilcoxon tests on vectors of data; the latter is also known as ‘Mann-Whitney’ test.
Best regards
The Wilcoxon rank sum test and the Mann-Whitney test are equivalent. People often refer to this test as the Wilcoxon-Mann-Whitney test to avoid confusion and to share the credit.
The test for paired samples is the Wilcoxon signed-rank test, and is different.
However, in R, both tests are performed with the wilcox.test function, by choosing different options. Another option are the wilcox_test and wilcoxsign_test in the coin package.
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