What is Spearman’s Rank Correlation Test?
Spearman’s Rank Correlation Test meaning a statistical test for correlation (statistical dependence) between a sequence of pairs of values. Using ranks eliminates the sensitivity of the correlation test to the function linking the pairs of values. It assesses how well the relationship between two variables can be described using a monotonic function (a function that either never decreases or never increases as its independent variable increases). It is a non-parametric alternative to correlation and it is used when the data do not meet the assumptions about normality, linearity and homoscedasticity
reference: Coral Reef Information System – Glossary