1 Association Rules

Association Rules is a popular and well researched method for discovering interesting relations between itemsets in large databases. We start from defining a few ways to measure association.

  1. Support: The support, \(\text{supp}(X)\), measures how popular an itemset (\(X\)) is. It is calculated as the proportion of transactions in the data set which contain the itemset.

    • We use Table 11 below to show that the support of {apple} is 4 out of 8, or 50%. Itemsets can also contain multiple items. For instance, the support of {apple, beer, rice} is 2 out of 8, or 25%. The support of {apple, beer} is 3 out of 8.