How to Calculate Mann-Whitney U Test
What is Mann-Whitney U Test?
The Mann-Whitney U test is the non-parametric equivalent of the independent t-test. It compares rank sums to test whether two groups have the same distribution, without requiring normality.
Step-by-Step Guide
- 1Rank all observations from both groups combined
- 2U₁ = n₁n₂ + n₁(n₁+1)/2 − R₁
- 3U = min(U₁, U₂)
- 4Compare to critical value table
Worked Examples
Input
Group 1: [4,5,6,8,7] · Group 2: [2,3,1,4,3]
Result
U = 3 → significant difference (n=5 each)
Ranks compared across both groups
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