Image: Euclid Analytics
From the retailer’s perspective, this information can be a virtual gold mine. For the first time they can easily track where customers go after they enter the store. They can identify repeat customers and first timers. They can find out whether shoppers are spending a lot of time in the toy aisle but rarely visit sporting goods or home appliances, and reconfigure the store layout accordingly. They can share data across different locations – to gauge whether the same customers spend more time in their discount outlets or shop at the locations closer to major freeway exits. They can even track people who walk by the store every day but never go in, or if more people enter after a window display is changed.
But even if Euclid doesn’t know who you are, the store does – the moment you plunk down plastic to buy something. Correlating that purchase with your location (ie, near the register) is probably as simple as matching time stamps between the transaction and the analytics log. And as mobile payments using Near Field Communications chips built into phones becomes more common, that process becomes even simpler.
Once the retailer has tied your MAC address to your identity, all kinds of fun things can happen. The store can send you discount coupons to entice you into aisles you rarely visit. If they have your phone number, the store could send you a text when you walk by, trying to lure you in. A retailer can marry that data to your online activities to further analyze who you are and how it can get you to spend more time and money in its stores, or sell that information to a third party.
And, assuming the retailer stores that data, it can hand it over to any legal authority with the appropriate paperwork.
[Update: Euclid has responded to -- and corrected -- some of these hypotheticals here.]