Association Rules and Frequent Itemsets

Apriori calculates rules expressing probabilistic relationships between items in frequent itemsets, indicating item co-occurrence probabilities.

For example, a rule derived from frequent itemsets containing A, B, and C might state that if A and B are included in a transaction, then C is likely to also be included.

An association rule states that an item or group of items implies the presence of another item with some probability. Unlike decision tree rules, which predict a target, association rules express correlation.