Question

For the table below, calculate the support and confidence of the following rules (show the fractional values, do not calculate with decimals):

broccoli -> rice
rice -> broccoli
tea -> beets
beets -> tea

Customer 1: broccoli, rice, tea
Customer 2: broccoli, tea, beets
Customer 3: broccoli
Customer 4: rice, tea, beets
Customer 5: broccoli

Answer 1

first we need to know basic formula of support and confidence.

Let a rule X -> Y is there.so,

support=no of times when X is purchased Y is also purchased / total no of transaction.

confidence=no of time both X and Y are purchased together / no of transaction in which X is there.

For first rule:

Broccoli -> rice

support=no of times when broccoli is purchased rice is also purchased / total no of transaction.

support=1/5.

  confidence=no of time both broccoli and rice are purchased together / no of transaction in which broccoli is there.

confidence=1/4.

Rule 2.

rice -> Broccoli

support=no of times when rice is purchased broccoli is also purchased / total no of transaction.

support=1/5.

  confidence=no of time both rice and broccoli are purchased together / no of transaction in which rice is there.

confidence=1/2.

Rule 3.

tea -> Beets

  

support=no of times when tea is purchased beets is also purchased / total no of transaction.

support=2/5.

  confidence=no of time both tea and beets are purchased together / no of transaction in which tea is there.

confidence=2/3.

Rule 4.

Beets -> tea

  

support=no of times when beets is purchased tea is also purchased / total no of transaction.

support=2/5.

  confidence=no of time both beets and tea are purchased together / no of transaction in which Beets is there.

confidence=2/2.