Confidence is defined as the probability of seeing the rule’s consequent under the condition that the transactions also contain the antecedent. Confidence is directed and gives different values for the rules X→Y and Y→X. Association rules have to satisfy a minimum confidence constraint, conf(X→Y)≥γ. Confidence is not down-ward closed and was developed together with support by Agrawal et al. (the so-called support-confidence framework). Support is first used to find frequent (significant) itemsets exploiting its down-ward closure property to prune the search space. Then confidence is used in a second step to produce rules from the frequent itemsets that exceed a min. confidence threshold. A problem with confidence is that it is sensitive to the frequency of the consequent Y in the database. Caused by the way confidence is calculated, consequents with higher support will automatically produce higher confidence values even if there exists no association between the items. … Confidence google