The proliferation of mobile phones has spawned a new research sector: mobile data analysis. The goal? To study new information concerning users’ social behaviours. In countries of the South, such research helps assess the spread of epidemics or the quantity of food resources—and thus saves lives. To get a clearer picture, UCL applied mathematics researchers analysed the great strides in mobile data analysis over the past 15 years.
For 15 years now, it’s been unthinkable to leave home without your mobile phone! It’s found in every pocket and using it has become more than a habit: it’s a fact of life. In 2015, 96% of the world population—6.8 billion people—possessed a mobile phone, up from 12% in 2000. The mobile phone has revolutionised how we communicate. Its proliferation has spawned a new research sector: mobile data analysis. Every day, millions of people, even in the remotest corners of the world, communicate and interact. These contacts generate data from which it’s possible to extract vital information about users’ social behaviours and mobility. They offer an overview of society’s evolution and needs. ‘With the development of mobile phones, it became apparent that it was possible to observe human behaviour in an unprecedented way’, explains Adeline Decuyper, a doctor of applied mathematics and research assistant at UCL. ‘Today we find that logical, but 15 years ago it was entirely new.’
No, the world is not a village
With UCL Rector Vincent Blondel and Gautier Krings, both doctors of applied mathematics, and supported by the FNRS, Dr Decuyper synthesised and studied research on 15 years’ worth of phone data analyses. They shared their conclusions in an article published in the European Physical Journal Data Science, in which they defined the methodologies used by researchers, highlighting call detail record (CDR) analysis. A CDR is a record generated during mobile communications. ‘When we call, the operator records data for billing purposes’, explains Dr Decuyper. ‘It’s not content, but rather the fact that customer A called customer B at a certain time, via connection by a certain antenna, for X amount of time. Everything is anonymised. Sometimes there’s more detailed information such as user age and gender, if the operator agrees to share them, but that’s increasingly rare for reasons of privacy protection.’
Several studies came to one notable conclusion: the world is far from being a village! While people have more opportunities to communicate, proximity still plays an important role in maintaining social bonds: distance shrinks the volume of calls.
Analysing mobility: essential in the South
In recent years, research has focused on countries in the South, where the penetration rate of mobile phones is on the rise. The stakes involved in mobile data research have evolved. ‘There’s great value in being able to analyse the movement of people’, says Dr Decuyper. ‘For example, we can assess how an epidemic is going to develop or estimate the population density of the remotest areas. It’s much more useful than here, in fact!’
A few years ago the mobile operator Orange launched Challenge Data for Development, a call for projects based on sharing the mobile data of Côte d'Ivoire, then Senegal, with hundreds of research teams. ‘It led to concrete proposals, such as redesigning Abidjan’s public transport network according to its residents’ needs.’ Dr Decuyper participated in a food shortage project with the United Nations and the World Food Programme. ‘It involved identifying populations most in need in terms of food access. In general, the World Food Programme works by sending people on site, which costs hundreds of thousands of dollars, and the information rapidly becomes outdated. Our project made it possible to cross-check phone data analyses with field survey results and draw conclusions. With mobile data, we can estimate household spending on food. We can predict carrot consumption, for example. From that, we can get a good idea of the food security level in each region and know where to send aid, if necessary. Using this data costs nothing, yet it can save lives.’
Privacy protection: not forgotten
Of course, these studies are based on sampling. Given the partial nature of this information, a margin for error exists. But while the sampling is imperfect, it’s nevertheless relevant: it concerns a significant proportion of the population (often 30% to 50%). Moreover, in some cases, the mobile data analyses are the only ones that can be rapidly implemented in a given territory, to survey the population, for example. ‘We always try to validate a maximum of observations’, insists Dr Decuyper. ‘Sometimes the degree of accuracy is uncertain, but it’s better than nothing at all.’ At a time when privacy protection is of paramount concern, scientists emphasise that their research is conducted in a regulated environment. They work with anonymised data, even though the richness of the information is therefore lost. They’re bound by a confidentiality contract and their role is also to expose potentially harmful uses and study how to defend against them.
A Glance at Vincent Blondel's bio
A Glance at Adeline Decuyper's bio
A Glance at Gautier Krings's bio