Executive Summary

International migration statistics (referred to as ‘migration statistics’ in this report) are vital in aiding our understanding of society. They are a key component of population statistics as well as being a key area of public and policy interest. However, it is also extremely challenging to measure migration accurately.

The Office for National Statistics (ONS) has been embarking on an ambitious programme to transform how it measures international migration. ONS has moved away from using the International Passenger Survey (IPS) to estimate migration and is undertaking an innovative programme based on the use of modelled estimates (tactical approach) and administrative data (strategic approach), instead of the survey.

Due to the importance of these statistics and the ambitious transformation programme underway, we conducted this review to ensure that the transformed migration statistics are trusted, high quality and of value in line with the Code of Practice for Statistics.

We have found that ONS is taking a sensible and well thought out approach to its development of data sources and methods for both the tactical and strategic approaches. It is effectively collaborating and engaging with academics and experts and publishing regular updates. However, despite this collaboration and engagement, we think there is a need to improve and broaden its user engagement. Despite its flaws, many IPS users were familiar with the its approach and its strengths and limitations. User engagement is vital to ensure that all users reach the same level of familiarity with the new approaches, otherwise they may not be confident in the approach. Engaging with both expert and less expert users – their questions, challenge and advice – will help refine and enhance the approach. This engagement will also help to manage expectations around what is possible.

The migration transformation is also taking place in the context of a wider transformation of population statistics and the backdrop of the pandemic. Clear and coherent communication of the migration changes in this context is essential to keep users engaged with the transformation programme. Population estimates and migration estimates should be coherent. This is one of the goals that ONS is aiming to reach. ONS is exploring Demographic Accounts as a method to draw together and achieve fully coherent estimates across population and migration through time. Communication around the migration transformation programme should be presented in this wider context to help users understand what data will be available when, how it can be used and any impacts on quality due to the pandemic.

In summary, ONS has been credible and robust in its development of the methods and data sources underpinning its transformation of migration estimates, and has engaged well with experts on these developments. It should build on this in two ways:

• improve and broaden its user engagement; and
• ensure clear and coherent communication of its migration plans in the context of the population and labour market transformation.

We fully support ONS’s transformation of its migration statistics and look forward to working with ONS to ensure that the transformed migration statistics serve the public good.