Over at Mashable, they have a short blurb from Shopkick on the problems with SmartPhone GPS. Shopkick makes a system that emits a non-audible tone that can be detected by smartphones and used to identify customers in various establishments for coupons and special offers, the goal hopefully being that it’s more accurate than GPS or WiFi based systems. Already in use in a few locations, ShopKick plotted various users in a few cities showing where they actually are (the green pins with ShopKick systems) versus where their smartphone things they are (the blue pins). The results are shown in the map above.
At first glance, you see ShopKick’s appeal. Looks how far some of those pins are off, several blocks in some cases. However, there’s one incredibly important piece of information missing from this map: Accuracy. All GPS systems report, in addition to their location, their Accuracy. I bet if you plot each of these points as a Circle, indicating the accuracy, you’ll see many of them actually overlap their real location. GPS systems take a little while to catch a signal, hence the reason most SmartPhones use aGPS, a modified version of GPS that starts with ground data like WiFi and Cell-towers to get an approximate lock while they wait for a Satellite signal to come in. This is why Google Maps on your iPhone typically puts your “blue pin” as a “big blue circle” and slowly hones in over the next 30-60s.
Visualizing accuracy and error is a critical part of information like this, and leaving it out is deceptive, borderline lying.
