Counting the number of mobile phones present in a detection zone is a complex task. We employ several computational models to calculate the number of mobile phones present, knowing that phones do not probe continuously. Our computational models are statistical/probabilistic, not deterministic. As a result, counts of visitors, visits, and unique visitors are delivered with digits after the decimal point (also known as "floats").

Phones are not probing every second, so our computational model estimates the likelihood that a phone that probed X seconds ago is still in the detection area. If one hundred phones probe at time X, but not subsequently, some increasingly smaller fraction of these phones will be present in the minutes following time X. Our models estimate the number of phones present, delivering the results of these calculations with digits after the decimal so that subsequent calculations do not lose precision. That said, the accuracy of the counts depends on the precision of the calibration.

The BlueZoo technology is suitable for measuring up to ten thousand phones in the detection area, though the upper limit may actually be higher. BlueZoo's secret sauce is our computational models that permit us to deliver excellent accuracy without perfect inputs. We choose among our several computational models based on the target environment.