Grocery data1. Given the following itemsets:

{A,B,C} {B,C} {A,B,C,D} {A,C,D} {C,D} {B,C} {B,D}

c) What is the interest of {A}->C, {B}->C, {A,C}->B, {B,C}->D ?

2. Apply the A-Priori Algorithm with support threshold 3 to the itemsets from problem 1.

3. If we use a triangular matrix to count pairs, and n, the number of items, is 20, what pair's count is in a[100]?

4. Assume you are given the following collection of twelve baskets, each of which containing three of the six items 1 through 6:

{1, 2, 3} {2, 3, 4} {3, 4, 5} {4, 5, 6} {1, 3, 5} {2, 4, 6} {1, 3, 4} {2, 4, 5} {3, 5, 6} {1, 2, 4} {2, 3, 5} {3, 4, 6}

Suppose the support threshold is 4. On the first pass of the PCY Algorithm we use a hash table with 11 buckets, and the set {i, j} is hashed to bucket ij mod 11.

a) By any method, compute the support for each item and each pair of items. b) Which pairs hash to which buckets? c) Which buckets are frequent? d) Which pairs are counted on the second pass of the PCY Algorithm?

5. For this question, you will need to use the Orange Canvas data mining software. You can find it at: http://orange.biolab.si/

Be sure to read the documentation and especially the following: http://docs.orange.biolab.si/widgets/rst/associate/associationrules.html#association-rules

Then download the file grocery-data.txt (from BlackBoard) and use it with the Orange Canvas software to answer the following questions:

a) Which rule has the most confidence?

b) If we consider rules with any confidence, for what support value do we arrive with only 10 rules?

c) Make a screenshot of the Orange schema (i.e. your workspace) you used to answer questions (a) and (b) and insert it.