More and more people missing from official data
Foreign aid cuts will worsen ‘quiet crisis’, say experts
Researchers are warning that millions of people around the world aren’t being counted in census and survey data, leaving policymakers in the dark about the populations they govern.
They say a ‘quiet crisis’ is unfolding with census data due to declining response rates and concerns about the accuracy of the data.
In a paper published in Science, researchers from the University of Southampton and Columbia University point to a ‘perfect storm’ of disruptions from the COVID-19 pandemic, declining confidence in institutions, and collapsing international support.
It says recent cuts to international aid budgets from the USA, the UK, and other European countries will worsen the situation.
“Lack of census data compromises all areas of public administration, but we don’t see these statistics in the same way as other vital infrastructure, like bridges or roads,” says Dr Jessica Espey, lead author of the paper from the University of Southampton and Deputy Director of its WorldPop research team, which provides data on population distribution, demographics and dynamics.
“When groups are not counted, they can be left off the policy agenda. That political underrepresentation and the inadequate resource allocation that follows can have pernicious effects.”
Decisions about where to build a hospital or how to allocate resources for schools rely on knowing how many people live where and who they are. This information is especially important during a crisis, such as an outbreak of disease or a natural disaster.
Censuses, a device of government administration since Roman times, provide these data allowing governments to direct resources and anticipate future challenges and opportunities, such as an ageing population or a burgeoning younger one.
But the percentage of the world’s population covered by up-to-date censuses, conducted every ten years, has declined. Additionally, 24 of the 204 countries that carried out a census between 2015 and 2024, representing a quarter of the world’s population, haven’t published their results.
Census post-enumeration surveys, which independently assess the completeness of a census, suggest a decline in accuracy and coverage. The 2020 US Census likely undercounted the US Latino population by 2.9 million people, while the 2022 South African census undercounted its overall population by up to 31%. The UN estimates that one in three Africans were not counted in the 2020 census round.
The COVID-19 pandemic disrupted traditional house-to-house interviews and impacted funding. Researchers also highlight growing distrust in national governments, with some communities fearing immigration-related law-enforcement or AI-supported decision-making will use their data against them, and others worried about the threat of data leaks and cyber-attacks.
In February of this year, the Trump administration cut support for the Demographic and Health Surveys (DHS) program, which provided vital data on populations across 90 countries for four decades, often filling gaps left by lack of census data. Other countries like the UK, France, and the Netherlands have reallocated development assistance to defence spending, reducing both direct assistance to countries and also to UN agencies that provide support on censuses and surveys.
“We live in an era of seemingly unlimited data, yet some of our most essential demographic information is deteriorating, introducing known and unknown bias into decision making,” says co-author Dr Dana Thomson from Columbia University.
The researchers say new technologies, such as AI-derived building footprints from satellite images, can support the planning and implementation of censuses and potentially reduce costs, pointing to recent successes in multiple countries that WorldPop has supported, such as the Democratic Republic of the Congo.
They also say governments need to do more to build trust, demonstrate how census data affects people's daily lives and be transparent about how this data is used to inform decisions.
Professor Andrew Tatem, a coauthor of the paper who leads WorldPop at Southampton, says: “In an era of growing challenges, from climate change to economic inequality, accurate population data is not a luxury – it is essential infrastructure for healthy, resilient, functioning societies.
“The current undercounting of populations creates a negative feedback loop, leaving governments with less accurate information on the communities most in need. This threatens both statistical accuracy and the very foundations of equitable governance.
“By combining technological innovation with renewed public trust and international cooperation, we can ensure that everyone is counted – and everyone counts.”
Disappearing People: how the global demographic data crisis threatens public policy is published in Science and is available online.
Contact
Steve Williams, Media Manager, University of Southampton, press@soton.ac.uk or 023 8059 3212.
Notes for editors
- Disappearing People: how the global demographic data crisis threatens public policy is published in Science. An advanced copy is available upon request.
- For Interviews with Dr Jessica Espey and Professor Andrew Tatem please contact Steve Williams, Media Manager, University of Southampton press@soton.ac.uk or 023 8059 3212.
- You can find out more about WorldPop here: www.worldpop.org
Additional information
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Journal
Science
Article Title
Disappearing people: A global demographic data crisis threatens public policy
Article Publication Date
19-Jun-2025
Decline in population data collection threatens global public policy
Summary author: Walter Beckwith
In a Policy Forum, Jessica Espey and colleagues argue that waning support for accurate collection and curation of population data worldwide threatens to compromise crucial evidence-based government planning. “We live in an era of seemingly unlimited data, where our digital activities may generate nearly constant information streams, yet some of our most essential infrastructure – demographic information – is deteriorating, introducing known and unknown bias into decision-making,” write the authors. Accurate population data are fundamental to effective governance. Most countries rely on national censuses, which are traditionally conducted every 10 years, to supply this information. But according to Espey et al., fewer nations are completing censuses, and many are undercounting marginalized populations. For example, at the close of the 2020 census cycle, 204 countries or territories – encompassing 85% of the world’s population – had conducted at least one census between 2015 and 2024. Yet by July 2024, 24 of these, representing roughly one-quarter of the global population, had not published their findings. This reflects a significant decline from the 2010 round, when 214 countries conducted and released census data, encompassing 93% of the global population. Moreover, even when censuses are carried out, they increasingly suffer from declining response rates and growing coverage errors – particularly in the undercounting of vulnerable populations such as ethnic minorities and young children. In the United States, for instance, the 2020 census likely missed nearly 3 million Latino individuals and close to 1 million children under the age of five.
In this Policy Forum, the authors outline several reasons for this general decline: eroding trust in institutions, COVID-19 disruptions, budget cuts to statistical offices, and collapsing international support for data collection programs. In order to address this “quiet crisis,” Espey et al. suggest adopting register-based systems, harnessing geospatial technologies and AI, and producing small-area population estimates. However, technical innovations alone are not enough, note the authors; governments must also restore public trust by showing how data informs daily life, ensuring strong privacy protections, and promoting collaboration across sectors. “In an era of growing challenges, from climate change to economic inequality, accurate population data are not a luxury – they are essential infrastructure for healthy, resilient, functioning societies,” write the authors.
Journal
Science
Article Title
Disappearing people: A global demographic data crisis threatens public policy
Article Publication Date
19-Jun-2025
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