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 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 on a bookseller's recommendation. These impulse buys are no coincidence, as retailers use sophisticated data analysis techniques to identify patterns that will drive retail behavior.

In years past, such recommendation systems were based on the subjective intuition of marketing professionals and inventory managers or buyers. More recently, as barcode scanners, computerized inventory systems, and online shopping trends have built a wealth of transactional data, machine learning has been increasingly applied to learn purchasing patterns. The practice is commonly known as market basket analysis due...