The Support and Confidence Given rule x&y=>Z Support,S=P(x∪YuZ) where AU B indicates that a transaction contains both X and y (union of item sets X and Y) of tuples containing both a &b/ total of tuples Confidence, C=P(ZXUY) P(Z XU Y) is a conditional probability that a transaction having iXUY also contains of tuples containing both X&y&z /# of tuples containing X&y6 Given rule X & Y => Z ◼ Support, S = P(X  Y  Z) where A  B indicates that a transaction contains both X and Y (union of item sets X and Y) [# of tuples containing both A & B / total # of tuples] ◼ Confidence, C = P(Z | X  Y ) P(Z | X  Y ) is a conditional probability that a transaction having {XY} also contains Z [# of tuples containing both X&Y&Z / # of tuples containing X&Y] The Support and Confidence