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Non-Parametric Tests

Wilcoxon Signed-Rank Test

Rank-based comparison for paired non-normal data.

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Method overview

When to use

Use for paired or before-after data when paired differences are not approximately normal.

Input requirements

Enter two equal-length numeric vectors. Values are paired by position.

Key assumptions

  • Data are paired correctly.
  • Zero differences are removed.
  • Differences are at least ordinal and roughly symmetric for the usual signed-rank interpretation.

Null hypothesis

H₀: the median paired difference equals 0.

Method used

Wilcoxon signed-rank statistic with normal approximation.

References

  • Wilcoxon F. Individual comparisons by ranking methods. Biometrics Bulletin, 1945.

Data input and results

Enter paired non-normal or ordinal measurements. Equal values are removed as zero differences.

No calculation has been performed.