non-parametric

The correlation coefficient is a measurement of correlation between two random variables. While its computation is straightforward, it is not readily applicable to non-parametric statistics.

A tutorial of performing statistical analysis with the Kruskal-Wallis test.

A tutorial of performing statistical analysis with the Mann-Whitney-Wilcoxon test.

A tutorial of performing statistical analysis with the Wilcoxon signed-rank test.

A tutorial of performing statistical analysis with the sign test.

A statistical method is called non-parametric if it makes no assumption on the population distribution or sample size.

This is in contrast with most parametric methods in elementary statistics that assume the data is quantitative, the population has a normal distribution and the sample size is sufficiently large.