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Census 2021 and Migration

By Boyana Buyuklieva, UCL

Migration – the movement of individuals or households from one place of usual residence to another is an important topic within geography. This is partly because individual choices, but also circumstances, manifest themselves as population behaviours and in turn, population behaviours set the context for policymaking, including where to place public services such as hospitals and police, where to invest money, such as through the government’s levelling-up agenda, and even who receives paper census forms rather than the digital version. Migration is also an important measure in political terms. It can be a highly ambiguous and divisive measure when governments set targets for net migration or when politicians discuss topics such as ‘brain drains’ or new development and regeneration schemes.

Data on migration are therefore an essential statistic with various practical (and political) uses. At a national level, mobility records underpin populations estimates that are essential for resource allocation and strategic decision-making, but also at an international level, the UK is required to measure and report on migration for various reasons, including, but not limited to, the United Nations’ Global Sustainable Development Goals.

The census data product

The census is important for migration research because it is the most exhaustive source of data for understanding how a population is distributed across space. It the most exhaustive source of data because of its scale (number of people questioned), scope (the geographic extent of the whole country), and specificity (topics and types of questions asked). It is collected in ten-year intervals in the UK by different bodies. These include the Office for National Statistics (ONS) for England and Wales, National Records of Scotland (although Scotland will be carrying out its census in 2022 rather than 2021) and Northern Ireland Statistics and Research Agency. These are coordinated at a UK level by Board of the UK Statistics Authority and then check by the Office for Statistics Regulation (OSR).

The first formal census in the UK was carried out in 1801 (created by the 1800 Population Act). Enumerators went door to door to in parishes across England and Wales for the open-ended purpose of ‘taking an account of the population of Great Britain, and of the increase or diminution thereof’. The context for the 1801 census was a decade of Napoleonic War expenses, which motivated an informed approach to nation-wide resource allocation. Though responses were initially gathered by appointed enumerators, as of 1970, the forms have become self-declared, which is important for gauging at the integrity of the data.

All the modern censuses are created under the legislative framework of the Census Act 1920. This makes their completion a legal requirement (subject to a fine when ignored!). It also ensures measures are taken for the planning and preparation of the big day and protection and preservation of all returns.

Within the UK, ‘official statistics’ are those that are either produced by the UK Statistics Board, or some government department, or alternatively, statistics outsourced by order of either of the two producers mentioned. There are three main types of statistics published, based on their degree of validation. The gold standard are National Statistics that have been assessed by the Office for Statistics Regulation. After these are experimental statistics – ones that are essentially under development.

Currently, the most detailed mobility data in existence are arguably experimental. This can include geo-located social media, mobile application usage data or call detail records. Despite the novelty and size of newer data sources, they ultimately rely on official census data to sanity-check their results. This however is undermined by the fundamental ethical concern: collecting detailed information about known individuals passively comes with no guarantee that it is representative in any way. For example, work done on snapshots of anonymised call records have raised concerns about the technical of using such datasets for describing movement patterns because where people call home is ambiguous and making assumption on this raises ethical concerns.

As of 2016, there have been discussions and reforms to the production UK migration statistics. This has led to some dataset has being officially re-classified from ‘National’ to ‘Experimental’ Statistics, leaving only a handful of audited National Statistics. Of this single largest source of information is the decennial census. It is also the only primary source that has coverage and availability across a wide space.

This means that CENSUS 2021 is an exciting event for migration research.

The work of Ravenstein (1885) – a geographer using census data – is widely considered the beginning of migration research. Almost a century later, in the late 1970s migration studies were spread across three main disciplines: demography, economics and sociology. The binding agents of this interdisciplinary line of inquire at the time were the US and UK census data sources. In the period between 2015-2018, more and more international statistical offices begin to feature in the wider literature thanks to wider developments and availability of spatial data.

The census 2021 will provide new data, but not insight or foresight on its own. It won’t tell us why individuals might move or provide a definitive demographic destiny of places. It will however, allow us to gain a better sense of when we move and how far, what neighbourhoods are like and the circumstances we call home in a most unprecedent, but potentially precedent-setting period of working from home due to COVID restrictions. Mobility or immobility is the ultimately the bridge between people and places. It why it will be important for geographers, along with economist, sociologist, and a host of other disciplines to keep an eye on migration and the census.


About the author: Boyana Buyuklieva is a doctoral researcher at the Centre for Advanced Spatial Analysis, UCL and member of the PGRG and GIScRG research groups. Boyana’s research is on quantitative spatial analysis at the intersection of housing, residential mobility, and demography. She is particularly interested in cities and technical literacy for governance and policy.

Suggested further reading

Catney, G. and Simpson, L. (2010), Settlement area migration in England and Wales: assessing evidence for a social gradient. Transactions of the Institute of British Geographers https://doi.org/10.1111/j.1475-5661.2010.00400.x

Jokisch, BD, Radel, C, Carte, L, Schmook, B. (2019). Migration matters: How migration is critical to contemporary human–environment geography. Geography Compasshttps://doi.org/10.1111/gec3.12460

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