to estimate where viruses might spread next, helping emergency
teams support displaced populations after natural disasters, or
showing planners how to improve city transport networks.[49] With
high-resolution GPS data, it’s even becoming possible to analyse
interactions between specific groups of people. For example, studies
have used mobile phone data to track social segregation, political
groupings and inequality in countries ranging from the United States
to China.[50]
If that last sentence made you feel slightly uncomfortable, you
wouldn’t be alone. As the availability of digital data increases,
concerns about privacy are growing too. Issues like inequality are a
major social challenge – and undoubtedly worthy of research – but
there is intense debate about how far such research should delve
into the details of our incomes, politics or social lives. When it comes
to understanding human behaviour, we often have a decision to
make: what is an acceptable price for knowledge?
Whenever my collaborators and I have worked on projects
involving movement data, privacy has been hugely important to us.
On the one hand, we want to collect the most useful data we
possibly can, especially if it could help to protect communities
against outbreaks. On the other, we need to protect the private lives
of the individuals in those communities, even if this means limiting
the information we collect or publish. For diseases like flu or
measles, we face a particular challenge, because children – who are
at high risk of infection – are also a vulnerable age group to be
putting under surveillance.[51] There are plenty of studies that could
tell us useful, interesting things about social behaviour, but would be
difficult to justify given the potential infringement on privacy.
In the rare instances where we do go out and collect high-
resolution GPS data, our study participants will have given consent
and know that only our team will have access to their exact location.
But not everyone has the same attitude to privacy. Imagine if your
phone had been leaking GPS data continuously, without your
knowledge, to companies you’ve never heard of. This is more likely
than you might think. In recent years, a little-known network of GPS