1. A SSOCIATION R ULES & THE A PRIORI A LGORITHM BY : J OE C ASABONA

2. I NTRODUCTION Recap o Data Mining o Three types Association Rules Apriori Algorithm

3. A SSOCIATION R ULES Most apparent form of Data Mining Objective: Find all co-occurrence relationships among data items Strength: Support & Confidence

4. S UPPORT Those who buy X buy Y, where X and Y are sets o X => Y.count = number of occurences n = number of total transactions Number produced is % of all transactions (T)

5. C ONFIDENCE % of transactions where X also contains Y Determines predictability of the rule Min Support and Confidence Determined.

6. E XAMPLE AR 1: Xbox ---> Controller o Support: 5/8 o Confidence: 3/5 AR 2: COD4 ---> Xbox o Support: 5/8 o Confidence: 2/5 AR 1 passes, AR 2 fails

7. A PRIORI A LGORITHM Generate all frequent item sets o All item sets with min support Generate all confident ARs from frequent item sets Downward Closure Property

8. G ENERATE F REQUENT I TEM S ETS Count supports of each individual item Create a set F with all individual items with min support Creates "Candidate Set" C[k] based on F[k-1]. Check each element c in C[k] to see if it meets min support Return set of all frequent item sets.

9. G ENERATE C ANDIDATE S ETS Create two sets differing only in the last element, based on some seed set Join those item sets into c Compare each subset s of c to F[k-1]- if s is not in F[k-1], delete it. Return final candidate set

10. R ULE G ENERATE Take Frequent Item Set F o If {F[1], F[2],...F[k-1]} => {F[k]}meets some min confidence, make it a rule o Remove last element from antecedent, insert into consequent, check again

11. O THER A LGORITHMS Eclat algorithm FP-Growth algorithm One-attribute-rule Zero-attribute-rule

12. S AMPLE D ATA Xbox, Controller, COD4 Xbox, COD4 Xbox, Controller Controller, COD4 Xbox, Rock Band, Controller Xbox, PS3 COD4, COD5, Rock Band COD4, Rock Band Min Support: 60% Min Confidence: 50%

13. R ERERENCES The Book I am using: Liu, Bing. Web Data Mining, Chapter 2: Association Rules and Sequential Patterns. Springer, December, 2006 Wikipedia: "Apriori Algorithm." http://en.wikipedia.org/wiki/Apriori_algorithm March 23, 2009 "Association rule learning." http://en.wikipedia.org/wiki/Association_rules March 25, 2009