Chapter 8. Finding Patterns – Market Basket Analysis Using Association Rules

Think back to the last time you made an impulse purchase. Maybe you were waiting in the grocery store checkout lane and bought a pack of chewing gum or a candy bar. Perhaps on a late-night trip to a convenience store for diapers and formula you picked up a caffeinated beverage or a six-pack of beer. You might have even bought this book on a whim after it was recommended to you by your favorite bookseller. In any case, it is no coincidence that gum and candy are located in checkout lanes, convenience stores stock beer in addition to diapers, and the bookstore seems to know exactly which book will catch your interest.

In years past, these type of recommendation systems were based on the subjective experience of marketing professionals and inventory managers or buyers. More recently, machine learning has been used to learn these patterns of purchasing behavior. Barcode scanners, computerized inventory systems, and online...