Chi-squared test

KDD

Part of Correlation Analysis.

${\chi }^2={\sum }_{i=1}^n{\sum }_{j=1}^m\frac{{\left(c_{ij}-e_{ij}\right)}^2}{e_{ij}}$

• zero → no Correlation
• larger value → more Correlation
• cells with very differenct actual count compared to expected count contribute the most