Center for Effective Global Action

Personal mobility data from mobile phones and other sensors are increasingly used to inform policymaking during pandemics,natural disasters, and other humanitarian crises. However, even aggregated mobility traces can reveal private informationabout individual movements to potentially malicious actors. This paper develops and tests an approach for releasing privatemobility data, which provides formal guarantees over the privacy of the underlying subjects. Specifically, we (1) introduce an algorithm for constructing differentially private mobility matrices, and derive privacy and accuracy bounds on this algorithm; (2) use real-world data from mobile phone operators in Afghanistan and Rwanda to show how this algorithm can enable the use of private mobility data in two high-stakes policy decisions: pandemic response and the distribution of humanitarian aid; and (3) discuss practical decisions that need to be made when implementing this approach, such as how to optimally balance privacy and accuracy. Taken together, these results can help enable the responsible use of private mobility data in humanitarian response.