User:JameiLei/Sandbox

Spearman's Rank
 * $$rs = 1- {\frac {6 \sum d_i^2}{n(n^2 - 1)}}$$

t-test
 * $$t = rs \left(\sqrt{\frac{df}{1-rs^2}}\right)$$

Pearson's
 * $$r=\frac{n(\sum x_iy_i)-(\sum x_i)(\sum y_i)}

{\sqrt{n(\sum x_i^2)-(\sum x_i)^2}~\sqrt{n(\sum y_i^2)-(\sum y_i)^2}}$$