Statistics Formulae

\bar{x} = \frac{1}{n}\sum_{i=1}^{n} x_i

s^2 = \frac{1}{n-1}\sum_{i=1}^{n} (x_i - \bar{x})^2

t = \frac{\bar{x}_1 - \bar{x}_2}{\sqrt{\frac{s_1^2}{n_1} + \frac{s_2^2}{n_2}}}

\chi^2 = \sum_{i} \frac{(O_i - E_i)^2}{E_i}