We use smartphone movement data to create human exposure indices for COVID-19. The immediate outputs of the project are ready-to-use data that will enable COVID-19 research requiring information on human movement. The two indices, LEX and DEX, study movements both within and across geographies in the United States. They measure location exposure stemming from cross-county movements and device exposure stemming from potential interactions at establishments, respectively. All indices are provided at a daily frequency at various granularities. In addition to these indices, we provide documentation and practical advice for using the data in research. These data are relevant for researchers and policy makers in examining human exposure to COVID-19.
Our analysis utilizes cell phone ping data covering millions of devices and millions of identified locations. The LEX is a matrix that utilizes smartphones pinged in a given location each day and incorporates the share of devices pinged in each location at least once during the previous two weeks. The DEX is a device-level index that incorporates the average exposure of people living in a county to other people within commercial venues. To calculate exposure, the index utilizes the number of distinct other devices the focal device interacts with through visits in a given establishment in a given day. The DEX index take into consideration that individuals sheltering in place may influence the quantity of cell phone pings for analysis. Examples using the LEX and DEX can be found in "Measuring Movement and Social Contact with Smartphone Data: A Real-Time Application to COVID-19" (Journal of Urban Economics: Volume 127, January 2022, 103328).