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Mann-Whitney U calculator
Paste your two groups of values. You get U, the tie-corrected z, a p-value and the effect size r — plus medians, which is what you should report alongside a rank-based test.
It tests whether one group's values tend to exceed the other's. Where the two distributions have a similar shape that approximates a median comparison; where they do not, the conclusion needs careful wording.
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This calculator was checked by Elaine Halliburton, Professor of Applied Statistics
In short
What is the Mann-Whitney U test?
The Mann-Whitney U test is a non-parametric alternative to the independent samples t-test. It ranks all values from both groups together and tests whether values from one group tend to be larger than values from the other. It does not assume normality and does not compare means.
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