Leveraging Facebook's Advertising Platform to Monitor Stocks of Migrants

Online advertising is the main source of revenue for social media companies. Facebook allows advertisers to target users with certain characteristics, such as age, sex, country of origin, education level, or topical interest. Before an ad is launched, Facebook's advertising platform provides an estimate of how many users match the provided criteria. This functionality, akin to a digital census of Facebook users, has so far been untapped for demographic research. We show the feasibility of estimating stocks of migrants within and across countries and discuss the potentials and limitations of the data. The lack of much-needed information about migrants, together with the rapid global expansion of social media use and the online advertising industry, offers new opportunities to study migration and to monitor progress toward achieving the goals of the United Nations 2030 Agenda for Sustainable Development.