Structured Procrastination on Cities, Transport Policy, Spatial Analysis, Demography, R
Every device which sends e-mail can be located at least at the country level by an internationally standardized code, the so-called IP address. Zagheni and Weber analyzed the countries derived from IP addresses for a set of messages sent by 43 million anonymous Yahoo! account holders between September 2009 and June 2011. In addition to the date and geographical origin of each message they compiled the self-reported birthday and gender of the sender. When a person started sending e-mail from a new location permanently, it was assumed that he or she had changed residence. This way they were able to calculate rates of migration from and to almost every country in the world.
