What this calculator does
Mann-Whitney U test (Wilcoxon rank-sum) works out compares two independent samples for a shift in distribution, using ranks instead of means. Enter your own figures above and the answer updates as you type: nothing is fixed in the code, so the result reflects exactly the numbers you supply.
The formula this calculator evaluates is printed under the tool and explained below, so you can check the working by hand or reuse it in a spreadsheet.
The formula
FormulaU₁ = R₁ − n₁(n₁+1)/2; μ_U = n₁n₂/2; σ_U² = n₁n₂/12·[(N+1) − Σ(t³−t)/(N(N−1))]; z = (U − μ_U)/σ_U
The inputs explained
| Field | What to enter |
|---|---|
| Sample A | A list of numbers, separated by commas or spaces. |
| Sample B | A list of numbers, separated by commas or spaces. |