Delphi receives data from SafeGraph, which collects anonymized location data from mobile phones. Using this data, we calculate the fraction of mobile devices that spent more than 6 hours in one location other than their home during the daytime, and average it over a 7 day trailing window. This indicator measures how mobile people are, and ought to reflect whether people are traveling to work or school outside their homes. See also our "At Away Location 3-6hr" indicator.