Facebook reveals number of migrants in the UK has been underestimated

Facebook data has helped a CPC Associate reveal the number of European migrants in the UK has been underestimated, according to new research published today in the journal Demography.

Currently, official migration statistics are collected and reported by the Office of National Statistics (ONS). But the new study, by Francesco Rampazzo from the Leverhulme Centre for Demographic Science, University of Oxford, used other materials, including the social media platform, to reveal that in 2018, there were likely to have been 25% more European migrants in the UK than official ONS statistics suggested and, for 2019, there may have been an additional 20%.

Francesco, in collaboration with a team including members of CPC and the University of Southampton, examined data from a range of sources, including the Facebook Advertising Platform, the Labour Force Survey (LFS), and country-specific information, to provide a more accurate picture. The project formed part of his ESRC-funded PhD.

In 2019, on ONS figures there were an estimated 3.6 million European migrants in the UK. But this new research suggests the real figure was more likely to be around 4 million.

Francesco explains: “Calculating migration is always going to be complicated. But the reason for the underestimate is the lack of quality of the official migration data. What is striking is our study reveals the underestimate is big. This is important because decision-makers require accurate evidence-based information to produce effective policies that affect people’s lives.

“Knowing the number of migrants in a region is important for planning….for example for schools and transport. The Covid-19 pandemic has proved that population estimates are not perfect; it has not been straightforward to know the actual numbers of residents in the UK for producing reliable estimates of vaccinated people.”

The ONS is aware of an undercount of 16% for net migration to the UK from eight EU countries in 2016. Currently, the UK uses a survey-based system to collect migration information and relies heavily on the International Passenger Survey (IPS), created in 1961 and which the ONS admits "has been stretched beyond its original purpose".

In comparison, this latest research combines statistics from the Facebook Advertising Platform, the Labour Force Survey, and unemployment and GDP (Gross Domestic Product) figures from each of the 20 countries included in the study.

“We looked at unemployment and GDP figures for each country to better understand the push and pull factors of migration. Why migrants might move away from their home country or return to it,” Francesco explains. “It is important to use a combination of different data sources and not rely on similar types...The hope is that this research contributes to a learning process and demonstrates a way to produce a more accurate understanding of the complex issue of international migration.”

Read Francesco's full 'Expert opinion' article on the University of Oxford website.

Francesco was an ESRC-funded PhD student in Social Statistics and Demography at the University of Southampton, and a Doctoral Fellow at the Max Planck Institute for Demographic Research (MPIDR). His main area of research for his fellowship explored the use of digital traces data combined with traditional data sources to estimate migration. He was supervised by Professor Jakub Bijak at the University of Southampton, Professor Agnese Vitali at the University of Trento, Ingmar Weber at the Qatar Computing Research Institute, and Professor Emilio Zagheni at MPIDR. You can read more about Francesco's PhD journey in the CPC newsletter, Changing Populations.

Posted 08/11/2021 16:19