Friedman test

The Friedman test is a statistical method used to compare three or more related groups to see if there are significant differences among them. It's often used when the same subjects are tested under different conditions or times. Instead of comparing raw data, it ranks the data within each subject, then analyzes these ranks to determine if the differences between conditions are likely due to chance or reflect real effects. This makes it useful for non-parametric data or when the assumptions of other tests, like normal distribution, aren't met.