1. A B Association Analysis is just elementary probability with new names
0.3
Pr{B}=0.3 A B
Pr{A and B}
= 0.2
Pr{A}
=0.5
0.1
0.4
= 1.0

2. Rule B=> A “people who buy B will buy A”
Support:
Support= Pr{A and B} = 0.2
Pr{A}=0.5= Expected confidence if there is no
relation to B. In other words, under independence,
Pr{A|B}=Pr{A} = 0.5.
Confidence:
Confidence = Pr{A|B}=Pr{A and B}/Pr{B}=2/3
?? Is the confidence in B=>A the same as the
confidence in A=>B?? (yes, no)
Lift:
Lift = confidence / E{confidence} =
(2/3) / (1/2) = Gain = 33% A B
0.2
0.1
0.3
0.4
Marketing A to the 30%
of people who buy B will
result in 33% better sales
than marketing to a random
30% of the people.
Link Graph:
Color and line thickness are
proportional to confidence