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 ?

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

• The Student's t-test
• The Welch's test