This study analyses e-mail data to evaluate global migration rates. A large sample of Yahoo! e-mail messages was extracted to estimate the movements of approximately 43 million anonymized users worldwide during a two-year period. This was done by mapping the geographic locations (e.g. city, county, or country) of the IP addresses from where users sent e-mail messages. These data were also linked to the self-reported age and gender of the e-mail users, allowing the researchers to estimate age- and gender-specific migration rates.
This study shows the potential of IP-addresses and e-mail data to supplement traditional data sources in producing estimations of global migration flows. The estimates from this study regarding the age profiles of migrants are consistent with existing administrative data sources. Even though uncertainty remains due to a selection bias (the study only analyses users of the Yahoo! e-mail client), this study allows to compare gender- and age-specific migration trends globally. In this regard, the study documents a general increase in human mobility, especially of women. Overall, this project demonstrates how innovative data sources can effectively supplement international migration statistics, in particular since e-mail data is capable to observe migration flows on a global level - unlike traditional data sources, such as surveys, censuses, and administrative data.
(Picture: © Max Planck Institute for Demographic Research)