Palo Alto-based startup Euclid Elements has raised $5.8 million in capital to fund a new offline analytics program designed for business owners. Euclid analytics is conceptually similar to Google Analytics for the real world but instead of tracking IP addresses, the company monitors smartphone Wi-Fi signals.

Euclid will install sensors inside brick-and-mortar stores that are used to detect Wi-Fi signals from customers' smartphones. The startup points out in their privacy policy that no personal data is gathered and the system cannot communicate with you; their sensors only detect signals from your smartphone and log its presence.

Euclid analytics can track all sorts of data which is then displayed on a convenient dashboard for the store owner or management to read from. Such data includes shopping behavior like foot traffic patterns throughout a store, customer loyalty (how often does a single person return to said store), how long each customer stays in the store and even window conversion rates, which detect if a potential customer checks out a window display outside the store and subsequently enters to shop.

Technically, the system works when your smartphone pings for a Wi-Fi signal in the area. Euclid's sensors detect this and hash the MAC address on the phone. The sensor isn't storing the actual MAC address but an identifier that represents that address. This allows the system to detect repeat customers.

There are some obvious drawbacks, such as the fact that not everyone owns a smartphone. Customers on feature phones or without a phone at all go unaccounted for. Furthermore if you have the Wi-Fi radio disabled on your phone, you won't be tallied either. Signs will be posted in stores where the service is installed instructing customers on how to opt-out of the data collection process.

Euclid has been conducting private trials in test markets but now the service is open to any US-based merchant. A subscription costs $200 per sensor per month and is said to cover a smaller-sized store. Those interested can sign up now and will be mailed a do-it-yourself installation kit.