Estimating International Migration: Immigration vs. Emigration

Every year, millions of people cross national borders in search of better jobs, education, or safety. Tracking these movements is one of the most challenging tasks in demography. International migration estimates help governments understand who is entering, who is leaving, and how these flows reshape the population. With India hosting the world’s largest emigrant population at 18.7 million people, understanding how immigration and emigration are measured is more than an academic exercise; it directly shapes economic planning, labour policy, and diplomatic relations.

Immigration and emigration: two sides of the same coin 🔗

Immigration refers to the movement of people into a country with the intention of settling there, either permanently or for a long duration. Emigration is the opposite, that is, the movement of people out of a country to live elsewhere. The same person is an emigrant from their country of origin and an immigrant in the country of destination. The United Nations standard definition treats a long-term migrant as a person who moves to a country other than that of their usual residence for at least a year.

The distinction matters because each flow has different consequences. Immigration adds to a country’s labour force, consumer base, and cultural mix. Emigration reduces the working-age population at home but often generates remittances, knowledge transfers, and diplomatic networks abroad. Together, they form what demographers call the migration component of population change, alongside births and deaths.

Why this distinction matters for population dynamics 🔗

Population change in any country is governed by the basic demographic equation: natural increase (births minus deaths) plus net migration (immigrants minus emigrants). When fertility rates fall, as they have in many Indian states, migration becomes a larger relative driver of population change. In states like Kerala, the steady outflow of workers has visibly altered age structures, leaving behind older populations and creating demand for elderly care services.

Methods for estimating international migration 🔗

Measuring migration sounds straightforward but is notoriously difficult. Emigration is one of the most difficult components of population change to estimate because of both data and methodological challenges, and there is no universal method that all countries follow.

Direct methods 🔗

Direct methods use records collected at the point of movement or settlement. These include:

Border statistics: Countries with strong border-control systems record arrivals and departures. India’s Bureau of Immigration captures this data through its immigration counters, but distinguishing tourists from long-term migrants remains tricky.

Population registers: Countries like Sweden and the Netherlands maintain continuous registers that record every change of residence. India does not maintain such a register, which makes estimation harder.

Surveys and censuses: The decennial census asks about place of birth and previous residence. The International Labour Organisation has developed migration modules for national labour force surveys to capture worker emigration and return migration, used in countries like Egypt, Thailand, and Ecuador.

Indirect methods 🔗

When direct data is missing, demographers use indirect techniques. The United Nations World Population Prospects methodology combines census data with information on fertility and mortality to calculate population changes that cannot be explained by natural factors alone. The unexplained residual is attributed to net migration. The residual method is widely used but produces estimates that lump immigration and emigration together rather than separating them.

Another technique is the mirror statistics method, which uses immigration data from destination countries to infer emigration from origin countries. For example, if the United States records 200,000 new immigrants from India in a year, that figure can serve as a proxy for emigration from India to the United States. This works best when destination countries keep good records.

Key measurement metrics 🔗

Three rates are commonly used in demographic analysis:

Immigration rate: The number of immigrants entering a country during a year per 1,000 persons in the receiving country’s population. If a country with 100 million people receives 500,000 immigrants in a year, the immigration rate is 5 per 1,000.

Emigration rate: The number of emigrants leaving a country during a year per 1,000 persons in the sending country’s population. This rate captures the intensity of outflow relative to the size of the home population.

Net migration rate: The difference between immigration and emigration rates, expressed per 1,000 people. A positive net migration rate means the country is gaining population through migration, while a negative rate signals losses. If a country with a total population of 10 million has a net migration of 20,000, the annual net migration rate is 2 migrants per 1,000 people.

These rates feed directly into population projections. A miscalculation of even a fraction of a per cent can throw off long-term planning for schools, hospitals, housing, and pensions.

Regional migration patterns: South Asia and beyond 🔗

South Asia is one of the most important migrant-sending regions in the world. The corridor between South Asia and the Gulf Cooperation Council (GCC) countries, that is, Saudi Arabia, the United Arab Emirates, Kuwait, Qatar, Bahrain, and Oman, has shaped labour markets on both sides for over half a century.

The Gulf corridor 🔗

The oil boom of the 1970s transformed migration patterns in South Asia. The Gulf states needed workers for construction, services, and oil extraction, while South Asian countries had a young, willing workforce. Slightly more than half of India’s 17.9 million emigrants in 2020 lived in Persian Gulf countries, with 3.5 million in the UAE alone.

This corridor is dominated by South Asian workers more broadly. According to one analysis of UN data, of the 28 million foreign workers in the Gulf countries, 16.9 million or 60 per cent comprise workers from South Asia, with 31.5 per cent from India, followed by Bangladesh at 11 per cent and Pakistan at 10.8 per cent.

A shifting geography within India 🔗

The internal map of emigration has also changed. In the early decades, southern states like Kerala, Tamil Nadu, and Andhra Pradesh dominated emigration flows to the Gulf. The trend of labour migration from India to the Gulf is now shifting from states like Kerala, Telangana, and Tamil Nadu to states like Uttar Pradesh and Bihar, with Uttar Pradesh sending mostly low-skilled labourers and Kerala sending a more skilled mix.

Movement toward advanced economies 🔗

The Gulf is no longer the only destination. In recent decades, students and skilled workers have been increasingly moving towards Europe, North America, and other advanced economies, shifting away from the traditional pattern of low-skilled labour migration to the GCC countries. The Kerala Migration Survey 2023 found that the share of emigrants choosing GCC countries dropped from 89.2 per cent in 2018 to 80.5 per cent in 2023, with more young people choosing destinations offering permanent residency.

The number of South Asian emigrants to Australia and New Zealand has doubled in three decades, and South Asian migration to Europe and North America has grown from about 2 million to nearly 9 million people. India now ranks second globally, after China, in the number of student migrants sent abroad.

Policy implications of migration estimates 🔗

Accurate migration estimates are not just numbers in a report. They drive policy in several powerful ways.

Remittances and macroeconomic planning 🔗

India is the world’s largest recipient of remittances. The top recipient country for remittances in 2024 was India, with an estimated inflow of $129 billion, followed by Mexico at $68 billion, China at $48 billion, the Philippines at $40 billion, and Pakistan at $33 billion. India’s share of global remittances has risen from around 11 per cent in 2001 to about 14 per cent in 2024. These flows finance current account deficits, support household consumption, and fund education and healthcare in migrant-sending regions.

Labour market and welfare policy 🔗

Estimates of emigrant workers help governments design protection schemes. India’s Ministry of External Affairs uses emigration clearance data to identify which states are sending vulnerable workers abroad and to negotiate bilateral labour agreements with destination countries. Schemes like the Pravasi Bharatiya Bima Yojana provide insurance to overseas workers based on this data.

Diaspora engagement 🔗

The Indian government engages its diaspora through Overseas Citizen of India cards, the Pravasi Bharatiya Divas, and investment channels for non-resident Indians. These programmes depend on knowing where the diaspora lives and what its skills are. According to Ministry of External Affairs figures, the total Indian diaspora is large, comprising non-resident Indians and persons of Indian origin spread across continents.

Global labour markets 🔗

Migration estimates feed into bilateral negotiations on quotas, recognition of qualifications, and workers’ rights. The Global Compact for Safe, Orderly and Regular Migration uses national estimates to coordinate international responses. Countries that systematically undercount emigration may underestimate the bargaining power they hold in such negotiations.

Challenges in data quality 🔗

Despite the importance of these estimates, data quality remains uneven. Many emigrants travel on tourist visas and overstay, never appearing in official emigration records. Undocumented migration is by definition difficult to count. Reliable record keeping of migration events is typically available only in the developed world, and the best existing methods to produce global migration flow estimates are burdened by strong assumptions. Bidirectional flows, including return migration, are often missed. Roughly a quarter of migration events globally consist of returns to an individual’s country of birth, yet most estimation models still struggle to capture this churn.

For policymakers, this means relying on a triangulation of sources, namely censuses, surveys, administrative records like passport and visa data, and mirror statistics from destination countries, to build a credible picture.

The future of migration measurement 🔗

New data sources are beginning to reshape the field. Mobile phone records, social media data, and digital identity systems offer near-real-time pictures of population movement. The U.S. Census Bureau, for instance, has recently combined administrative data with survey data to make net international migration estimates more responsive to short-term fluctuations in immigration, capturing pandemic-era declines and post-pandemic surges.

For South Asian countries, building such responsive systems is the next frontier. As migration becomes more diverse in destinations, skills, and durations, single-source estimates will not suffice. Combining traditional demography with newer digital data, while protecting privacy, will define the next generation of migration statistics.

What do you think? If a country systematically underestimates its emigrant population, which policies are most likely to suffer, and which groups within society pay the highest price for that statistical gap? How should South Asian countries balance the economic benefits of large emigrant flows against the social costs of losing skilled workers and family members?

References

1. https://documents1.worldbank.org/curated/en/099714008132436612/pdf/IDU1a9cf73b51fcad1425a1a0dd1cc8f2f3331ce.pdf
2. https://www.ons.gov.uk/peoplepopulationandcommunity/populationandmigration/internationalmigration/methodologies/methodstoproduceprovisionallongterminternationalmigrationestimates
3. https://www.unece.org/fileadmin/DAM/stats/groups/suitland/SWG_emigration_Jensen_UNECE.pdf
4. https://link.springer.com/article/10.1007/s13524-017-0622-y
5. https://ourworldindata.org/countries-measure-immigration-accurate-data
6. https://sociology.institute/diaspora-transnational-communities/indian-diaspora-global-presence/
7. https://medium.com/@indiamigration/indians-in-the-gulf-the-other-side-of-the-story-2870995eb748
8. https://www.ispionline.it/en/publication/the-evolving-patterns-of-south-asian-migration-to-the-gulf-states-191492
9. https://blogs.worldbank.org/en/peoplemove/in-2024–remittance-flows-to-low–and-middle-income-countries-ar
10. https://www.icwa.in/show_content.php?lang=1&level=1&ls_id=14463&lid=8868
11. https://www.pnas.org/doi/10.1073/pnas.1722334116
12. https://www.census.gov/newsroom/blogs/random-samplings/2024/12/international-migration-population-estimates.html