Imagine you are given a sample set of random transactions from an electronics store. assume that there are x transactions in this sample set. this retail store sells macbook pro (mbp), ipod, ipad, and other electronic goods. the number of purchases that include mbp in the database is 500. there were 400 transactions where the customer bought both ipad and mbp. the number of transactions that had ipod is 600, and the likelihood that someone would buy ipod (by itself or with another product) is 0.30.
now, you are interested in knowing more about the following two association rules:
rule a: if a person buys mbp then he/she is likely to buy ipad.
rule b: if a person buys ipod then he/she is likely to buy ipad.
after running a data mining software you found the following information:
rule a: lift ratio is 3.0
rule b: lift ratio is 2.5
confidence of a?