Mann-Whitney U Test Calculator

Mann-Whitney U Test Calculator

This calculator performs the Mann-Whitney U test (also called Wilcoxon rank-sum test), which compares two independent groups to determine if their distributions differ.

Null hypothesis: The distributions of both groups are equal.

Group 1 Data (comma separated):

Group 2 Data (comma separated):

Significance level (α): 0.01 (1%) 0.05 (5%) 0.10 (10%)

Test Results

About the Mann-Whitney U Test

The Mann-Whitney U test is a nonparametric test that compares two independent groups. It's used when your data isn't normally distributed or when you have ordinal data.

How to interpret results:

• U value: The test statistic - lower values indicate greater difference between groups
• p-value: Probability that the observed difference occurred by chance
• If p-value ≤ α: Reject null hypothesis (distributions are different)
• If p-value > α: Fail to reject null hypothesis (no significant difference)

Note: This calculator uses a normal approximation for p-value calculation, which is appropriate for sample sizes > 20. For smaller samples, exact p-values should be used.