# 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** 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 normality.

# How to use it on EasyMedStat ?

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