Question

In the context of Market Basket Analysis and association rules, consider the following data gathered from a preliminary analysis of Market Baskets for four products P, Q, R and S. Out of a total of 12 baskets, 8 contained P, 3 contained Q, 7 contained R and 4 contained S. Further, P and Q together were found in 2 baskets, P and R together in 6 baskets, R and S together in 1 basket, and Q and R together in 3 baskets.

a) Calculate the Support, Confidence and Lift for the association rule P-->R. What is your conclusion? (5 Points)

b) Calculate the Support, Confidence and Lift for the association rule S-->R. What is your conclusion? (5 Points)

Answer 1

Given

Total baskets - 12

P - 8

Q - 3

R - 7

S - 4

P and Q - 2

P and R - 6

R and S - 1

Q and R - 3

a) For the association P --> R

Support (P+R) = How many times both P,R out of all all baskets

= 6/12 => 0.5

Confidence(P -->R) = Support(P+R)/Support(P)

= 0.5/0.667 (as p contained in 8 baskets out of 12)

= 0.75

Lift = Confidence(P -> R) / Support(R)

= 0.75/0.5833 (As support(R) is 7/12 = 0.5833)

= 1.285

b) For the association ( S --> R)

Supoort (S+R)= 1/12 = 0.0833

Confidence(S -->R) = Support (S +R)/Support (S)

= 0.0833/ (0.333) (as the support (S) is 4/12 = 0.333)

= 0.25

Lift = Confidence (S --> R) /Support (R)

= 0.25/0.5833

=0.43