This allows the phone to do a quick shorthand calculation to provide GPS satellite data based on nearby Wi-Fi hotspots and cell tower data, instead of phoning home ET-style.
In both cases, several unrelated types of calculation, using independent data sets, and running on a range of computers in different organisations that may not fully trust one another, have to be threaded together to achieve a coherent answer.
However, the precision of this calculation is somewhat to be questioned because it is based on 2011 data and also because it excludes the banks' huge financial trading activities.
But I do believe that when the initial estimates came that there were -- it was 5, 000 barrels spilling into the ocean per day, that was based on satellite imagery and satellite data that would give a rough calculation.