Statistics/Testing Data/Spearmans

 Spearman Rank- Correlation coefficient 

Spearman developed a method of measuring rank correlation known as spearman rank correlation coefficient. It is generally denoted by rs. There are three cases while calculating Spearman rank correlation coefficient:

Case i    When ranks are given

Case ii   When ranks are not given

Case iii  Repeated ranks

The formula for calculating Spearman rank correlation coefficient is same for case i and ii. The formula is,

$$r_s = 1-\frac {6\sum \!\,d^2} {n(n^2 - 1)}$$

Where,

n = The number of items or individuals being ranked

d = $$R_1 - R_2 $$

$$R_1$$ = The rank of items with respect to first variable

$$R_2$$ = The rank of items with respect to second variable