A short-cut formula for Chi-square test a 2 by 2 table

$$\begin{array}{|c|c|c|} \hline a & b & (a+b)\\ \hline c & d & (c+d)\\ \hline (a+c) & (b+d) & n\\ \hline \end{array}$$

$$\chi^2_1 = \frac{n(ad-bc)^2}{(a+b)(c+d)(a+c)(b+d)}$$

－－ February 17, 2017更新 －－

$$|MCC| = \sqrt{\frac{\chi^2}{n}}$$