In our latest blog Statistics Regulator Gillian Fairbairn discusses the complexities of tracking migration and the importance of migration statistics…
What do Canada geese, wildebeest and humpback whales all have in common?
They migrate. Every year, Africa’s wildebeest herds travel across the continent in search of greener pastures, humpback whales move from one end of the planet to the other between feeding and breeding grounds, and Canada geese migrate south every year to warmer climates during the winter months. For these animals, migration reflects a move towards resources and away from threats.
We also see migration of people. Whilst most people will live close to where they were raised, some will move across the world, seeking out employment, education or personal connections, or simply exploring the world we live in. Others move away from difficult circumstances, political instability, war or a lack of resources.
All of this moving around doesn’t just impact the individual migrants. It also affects the areas being migrated to and from. Increases in population through immigration may increase demand for local services, for example, healthcare or education, as well as increasing local economic activity. Conversely, decreases in the population through emigration may reduce the demand and staff available to local services or have economic impacts, such as changing the local skills mix. As a result, official statistics on migration attract a lot of attention and are often covered by the media and discussed by government officials. As such, the regulation of these statistics is a priority at the Office for Statistics Regulation (OSR).
Regulating migration statistics
Back in 2022, OSR published its review of migration statistics produced by the Office for National Statistics (ONS). At the time, ONS, the producer of long-term international migration estimates was in the early stages of its plans to change the data sources for its long-term international migration statistics. Whilst ONS had plans to move towards estimating migration using administrative data , the COVID-19 pandemic brought a temporary stop to the International Passenger Survey (IPS) which was the main data source for migration estimates at the time. This accelerated the urgency of moving to a different data source to meet a pressing user need for high quality migration estimates. Our report highlighted ONS’s credible and robust approach to developing migration estimates. But it also noted that improvements should be made in how ONS engages with users, and it should ensure clear and coherent communication of its plans for migration statistics. Since we published our report, ONS has made significant progress towards meeting our recommendations, particularly with its user engagement. However, it still faces challenges in the production of migration estimates, particularly around revisions and communicating uncertainty. In December 2023, we published a follow up to our earlier review. The follow-up report recognised ONS’s progress and closed most of the recommendations that we set out in our initial review.
ONS revises its estimates after publication to reflect both where assumptions are updated with actual travel data and additional methodological developments. Some of these revisions have been significant and, in line with our expectations, ONS is working to understand and explain them to users. ONS is also working to address concerns with measuring the migration of British nationals, which is currently reliant on the IPS. The IPS arrivals survey was terminated last year so ONS is exploring alternative data sources for measuring these migrants.
Casework on migration statistics
Alongside ONS’s long-term international migration estimates, the Home Office produces a wide range of statistics describing the operation of the UK’s immigration system, which include statistics on people arriving in the UK through irregular migration, asylum and visa applications. We support and engage with the Home Office regularly, particularly through our casework function, where we respond to any queries or concerns raised by anyone about the production or use of statistics, including organisations and members of the public.
A theme in our casework relating to Home Office statistics has been their transparency. For example, figures were sometimes being used in the public domain by government officials ahead of publication, which falls short of our expectations in line with the Code of Practice for Statistics where we would expect statistics to be released in an open and transparent manner that promotes public confidence. Following a constructive letter exchange between our Director General and the Permanent Secretary at the Home Office, we have seen improvements to practice, with statistics being communicated in a clear and transparent way and interim official statistics publications used where appropriate.
Migration is an important topic that is at the centre of lots of public debate, and it is important that statistics are used to get under the surface of complex policy questions. But sometimes we see instances where the Home Office statistics are used incorrectly or unclearly in public debate, which can lead to misunderstanding or misrepresentation of the data. In addition to regulating the production of statistics, we use our voice to stand up for the appropriate use of statistics. So, for example, when concerns were raised with us that ministers used incorrect asylum backlog statistics, we investigated and publicly responded to stand up for the correct use of statistics in the public domain.
Final thoughts
Combined, ONS and the Home Office are providing users with a wealth of information on who is moving in and out of the UK and why. Whilst OSR recognises the good work carried out by these official statistics producers, it is OSR’s role to ensure that these official statistics are of sufficient trustworthiness, quality and value and that they are used appropriately to inform public debate. In addition to our publications, our statistics regulators engage regularly with statistics producers to provide ongoing support and guidance, often before any issues arise. This direct engagement enables us to have a positive impact on official statistics.
Tracking the migration of any species has its challenges. Imagine trying to attach a tracking device to a humpback whale which can cover thousands of kilometres of remote and inaccessible habitats. Perhaps the expectation is that measuring human migration should be more straightforward. However, complex visa systems, entry routes and unexpected political events can create significant challenges that might encourage even the most knowledgeable migration statisticians to go fishing instead!