In [[Association Rules|association rules]], Zhang's metric is a [[Error Metrics|metric]] that measures both association and dissociation. It is computed using the [[Leverage of an Association Rule|leverage]] and [[Support of an Item Set|support]] as:
$
\text{zhangs metric}(A \rightarrow C) =
\frac{
\text{leverage}(A \rightarrow C)
}{
\max \begin{cases}
\text{support}(A \rightarrow C) \times (1 - \text{support}(A)), \\
\text{support}(A) \times (\text{support}(C) - \text{support}(A \rightarrow C))
\end{cases}
}
$
Lies within the $[-1,1]$ interval, and a positive value indicates association while a negative value indicate dissociation.