Nature 453, 779–782 (2008)

The human mobility study relied on an anonymized billing dataset that was previously recorded by a mobile provider as required by law and billing purposes, and not for the purposes of this project. The research was reviewed and approved by the Institutional Review Board (IRB) at the US Office of Naval Research, the main sponsor of the project, and has approval from the Northeastern University’s IRB as well, the institution where the work was carried out. As part of the IRB review, the first author, who handled the data, and the PI participated in ethics training sessions at the outset of the study.