Spearman's Rank Correlation Coefficient

Description:

• Used to measure the correlation between the order or rank of two variables.
• Correlation between actual rank (of y) and supposed ranking (of x)
• $R=1-\frac{6\sum d_i^2}{n(n^2-1)}$
  • where $n$ is the number of pairs of data
  • $d_i$ is the difference between the rankings in each set of data. ($|supposed-real|$)
    • rank of x - rank of y
• The value of $R$ can be interpreted in exactly the same way as the ordinary correlation coefficient
• $-1\le R\le 1$