That would leak if there are multiple data points. In the extreme case, two points just either side of the 3 mile circle resolution would locate precisely (wher

That would leak if there are multiple data points. In the extreme case, two points just either side of the 3 mile circle resolution would locate precisely (where the two circles touch). Given N points within M meters or so, which is roughly what you get for multiple measurements of "home" with an error on the measurement, I think you could have a reasonable stab at deriving the location from an estimate of the error on the geolocation plus which circles they fell into. All in same circle makes near centre more likely than near edge. edit: daily check in, so all the above needs is a tendency to check in from roughly the same location each day.