How Retail Stores Track You Using Your Smartphone (and How to Stop It) (2013)
lifehacker.com

... The New York Times broke the story earlier this week that a number of retail stores are either experimenting with or actively using technology that uses your phone's Wi-Fi to track your movements around the store. We're not talking about location within a few meters either"we're talking about exact location.

Nordstrom, the store that the New York Times focuses on in its piece (although it's not the only one doing this) installed sensors around some of its stores that would scan for smartphones with Wi-Fi turned on and scanning for networks. The sensors would then make note of the device's MAC address (an address that's unique to your phone) and use it to identify and follow the device as it moves about the store. Information about how frequently that MAC address visits the store, which departments it visits when it's in the store, how long it stays in each department, and how long it stays in the store. Granted, you are not your phone's MAC address, but if you carry your phone with you all the time, you may as well be. As the NYT explains:

Nordstrom's experiment is part of a movement by retailers to gather data about in-store shoppers' behavior and moods, using video surveillance and signals from their cellphones and apps to learn information as varied as their sex, how many minutes they spend in the candy aisle and how long they look at merchandise before buying it.

All sorts of retailers " including national chains, like Family Dollar, Cabela's and Mothercare, a British company, and specialty stores like Benetton and Warby Parker " are testing these technologies and using them to decide on matters like changing store layouts and offering customized coupons.

Combined with in-store cameras, those sensors can do an impressive job of following an individual around the store, examining what they're looking at, and how they react to the products they consider. The video at above is from the New York Times' article on the topic, and shows you how closely the system can monitor an individual's movements. The video below, from Revision3's TechFeed news program, also does a great job of walking you through the technology and how accurate it can actually be. ...