How Stores Track Their Shoppers

An update on stores' efforts to see where you go once you step inside.

You’ve seen it happen. One day, you’re aspirationally browsing performance outerwear online; the next day, you’re seeing ads for Primaloft and Gore-Tex on every website you visit. That’s the power of tracking people while they’re shopping—even if they don’t buy anything—and brick-and-mortar stores want to get in on that action, too. They just need a way to record where their customers go, the way websites do.

MIT Technology Review recently took a look at progress in indoor tracking. Watching where people go inside buildings, where GPS can’t yet reach, is a little more challenging than keeping tabs on people outdoors or online. Nevertheless, MIT Technology Review names a few U.S. stores that have tried the technology, including Home Depot, Nordstrom, Family Dollar and American Apparel. The article also includes a helpful chart of the different methods of tracking stores use. Most ping customers’ smartphones somehow. Stores may also use cameras to monitor shoppers.

Besides just knowing what you look at, such data help stores better lay out their displays, cashiers and escalators; learn characteristics of their customers, such as gender and age; identify repeat customers and more. Some systems are even calibrated to detect people’s moods, The New York Times reported in July.

Customer reactions to these systems are mixed. Nordstrom stopped using its smartphone Wi-Fi tracking system in May, in part because of customer complaints, a spokeswoman told The New York Times. (The store had posted signs telling customers about what it was doing.) Others, however, may find coupons helpful. You can even willfully sell your physical-store shopping data, The Times reports, via a smartphone app.