Friedman Test Calculator
This calculator is designed for researchers and data analysts to perform the Friedman Test, a non-parametric test for detecting differences in treatments across multiple test attempts.
Data Source and Methodology
All calculations are rigorously based on the formulas and data provided by authoritative statistical sources. Learn more.
The Formula Explained
The Friedman Test formula is: $\chi^2 = \frac{12}{n k (k + 1)} \sum (R_j^2) - 3n (k + 1)$
Glossary of Terms
- Number of Groups: The different groups being compared.
- Number of Observations per Group: The number of observations within each group.
- Test Statistic (Q): The calculated statistic value for the test.
- P-Value: The probability value indicating the significance of the results.
How It Works: A Step-by-Step Example
Suppose you have three groups with five observations each. Input these values in the calculator and click "Calculate" to see the test statistic and p-value.
Frequently Asked Questions (FAQ)
What is the Friedman Test?
The Friedman Test is a non-parametric statistical test used to detect differences in treatments across multiple test attempts.
When should I use the Friedman Test?
Use it when you have repeated measures data or matched observations across multiple conditions.
How is the p-value interpreted?
A small p-value (typically ≤ 0.05) indicates strong evidence against the null hypothesis, suggesting that at least one group differs.
Is the Friedman Test parametric?
No, it is a non-parametric test, which means it does not assume a normal distribution of the data.
Can I use the Friedman Test for two groups?
While you can, it is more common to use the Wilcoxon signed-rank test for two matched groups.