Mann Whitney U Calculator
mann-whitney u calculator. Get instant, accurate results. Enter values for instant results with step-by-step formulas.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator
Mann Whitney U Calculator
Calculator
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Formula: U₁ = n₁n₂ + n₁(n₁+1)/2 - R₁
Worked example — U statistic with ranks
Formula
U₁ = n₁n₂ + n₁(n₁+1)/2 - R₁
Non-parametric test comparing two independent groups without assuming normality.
Worked Examples
Example 1: Two groups
Problem:G1:[3,4,6,8,9] G2:[1,2,5,7,10]
Solution:Rank and compute U
Result:U statistic with ranks
Frequently Asked Questions
What does the Mann-Whitney U test measure?
The Mann-Whitney U test evaluates whether two independent groups come from the same distribution, specifically testing whether observations from one group tend to have larger or smaller values than observations from the other group. U represents the number of times a value from one group outranks a value from the other group across all possible pairings.
When should I use Mann-Whitney U instead of an independent samples t-test?
Use Mann-Whitney U when data is ordinal, when distributions are heavily skewed or non-normal (particularly with small samples), or when significant outliers are present. The independent t-test is preferred when normality holds because it has more statistical power. Mann-Whitney is also appropriate when comparing groups with very different shapes even if sample sizes are large.
What are the assumptions of the Mann-Whitney U test?
The two groups must be independent; observations within each group must be independent of each other; the measurement scale must be at least ordinal; and both distributions should have the same shape (though not necessarily normal) to interpret the test as comparing medians. It does not require normal distributions or equal variances, making it robust in a wide range of situations.
Reviewed for accuracy by Manoj Kumar, Mathematics Educator · Editorial policy
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