The lift [[Error Metrics|metric]] of an [[Association Rules|association rule]] measures how much more often the antecedent and consequent of a rule $A \rightarrow C$ occur together than we would expect if they were statistically independent. It is computed based on the [[Confidence of an Association Rule|confidence]] and [[Support of an Item Set|support]] as per: $ \text{lift}(A \rightarrow C) = \frac{ \text{confidence}(A \rightarrow C) }{ \text{support}(C) } $ It lies in the $[0,\infty]$; if $A$ and $C$ are independent, the lift score will be exactly 1. If the lift score is 2, $C$ is twice as likely to appear when $A$ appears.