Nonparametric
Mann-Whitney U test
Compares two independent groups by ranks.
Variables
- Dependent variableContinuous · Ordinal — 1
- Grouping variableNominal · Ordinal — 1
Options
- Alternative hypothesisTwo-sided · One-sided (greater) · One-sided (less)
- Continuity correction
What it reports
U, Z, p; rank-biserial correlation; median with both IQR bounds.
scipy+formula · Open the accuracy report
When does this apply?
The same design as the independent-samples t-test — two independent groups, the outcome in one column and the group label in a second — but the comparison is by ranks rather than means, so the outcome may also be ordinal. The grouping column must be categorical: a numeric 0/1-coded column is not accepted here. The output is U, Z, p, and the rank-biserial correlation with a confidence interval.