Spearman's rank correlation coefficient

In mathematics and statistics, Spearman's rank correlation coefficient is a measure of correlation, named after its maker, Charles Spearman. It is written in short as the Greek letter rho (${\displaystyle \rho }$) or sometimes as ${\displaystyle r_{s}}$. It is a number that shows how closely two sets of data are linked. It only can be used for data which can be put in order, such as highest to lowest.

The general formula for ${\displaystyle r_{s}}$ is ${\displaystyle \rho =1-{\cfrac {6\sum d^{2}}{n(n^{2}-1)}}}$.

For example, if you have data for how expensive different computers are, and data for how fast the computers are, you could see if they are linked, and how closely they are linked, using ${\displaystyle r_{s}}$.