---
title: The Mann-Whitney's test
description: "\"The Mann-Withney test is a non-parametric test used to compare two medians from two independent groups. It is an alternative to the Student t-test when…"
---

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# The Mann-Whitney's test

# Definition

The **Mann-Withney** test is a non-parametric test used to compare the distribution of a numeric variable from two independent groups. It is an alternative to the [Student t-test](https://help.easymedstat.com/support/solutions/articles/77000362978-the-student-s-t-test-for-unpaired-data?hsLang=en) **when the data doesn't follow a normal distribution**.

In practice

The Mann-Withney's test is usually when the number of participants per group is \< 30 or when the distributions of the two samples do not respect the assumption of <https://help.easymedstat.com/support/solutions/articles/77000356202-the-shapiro-wilk-s-test?hsLang=en>[normality](https://help.easymedstat.com/support/solutions/articles/77000356202-the-shapiro-wilk-s-test?hsLang=en).

# How to use it on EasyMedStat ?

1. Go to Statistics \> Test variables
2. Select a Numeric variable you would like to compare between the two groups
3. Select a Yes-No variable to create groups of patients
4. Click on "Which tests can I do ?"
5. Click on "Compare values of ..."

# See also

- <https://help.easymedstat.com/support/solutions/articles/77000408441-analysis-of-variance-anova-?hsLang=en>[The Student's t-test](https://help.easymedstat.com/support/solutions/articles/77000362978-the-student-s-t-test-for-unpaired-data?hsLang=en)
- [The Welch's test](https://help.easymedstat.com/support/solutions/articles/77000401220-the-welch-s-test?hsLang=en)

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