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 0.3+0.2+0.1+0.4 = 1.0

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) = 1.33 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