Порівняння методів

	Migrant Stock Estimation	Migration Flow Estimation from Stocks
Галузь	Migration Studies	Migration Studies
Родина	Process / pipeline	Process / pipeline
Рік появи	1983	2013
Автор методу	United Nations Population Division (standard measurement conventions)	Guy J. Abel; Guy J. Abel & Joel E. Cohen
Тип	Cross-source pipeline for counting the resident migrant population	Demographic-accounting pipeline for deriving migration flows from stocks
Основоположне джерело	United Nations (1983). Manual on Methods of Estimating Internal Migration (Manual VI). Population Studies No. 47. New York: United Nations.	Abel, G. J. (2013). Estimating Global Migration Flow Tables Using Place of Birth Data. Demographic Research, 28, 505-546.
Інші назви	Foreign-Born Stock Estimation, International Migrant Stock, Migrant Population Counting, Stock-Based Migration Measurement	Stock-to-Flow Migration Estimation, Demographic Accounting of Migrant Stocks, Flow-from-Stock Method, Abel Stock-Differencing Method
Пов'язані	3	3
Підсумок	Migrant stock estimation answers a deceptively basic question: how many migrants are living in a place at a given moment? Unlike migration flows, which count moves over an interval, a stock is a cross-sectional count of people whose origin differs from their place of residence — most commonly the foreign-born, but sometimes the foreign-national or those who have lived abroad. The United Nations measurement conventions, set out in its migration manuals, fix the core definitions (place of birth versus citizenship, duration thresholds, usual residence) and the at-risk concepts that make stocks comparable. In practice the analyst rarely has one clean source: censuses give place-of-birth tables but miss recent or irregular arrivals, population registers give continuous citizenship-based counts but vary in how they handle departures, and surveys give detail but suffer sampling error. Migrant stock estimation is therefore a pipeline that compiles these sources, harmonizes their differing definitions and geographies, and adjusts for undercount, overstay, and double counting, drawing on the same comparability concerns Bell and colleagues raised for internal migration. The output — a coherent count of migrants by origin, age, and sex — underpins integration policy, flow estimation, and the denominators of countless migration indicators.	Migration flow estimation from stocks reconstructs the unobserved movement of people between countries from something that is observed: how many foreign-born residents each country holds, broken down by country of birth, at two points in time. Most countries report migrant stocks — the number of people living abroad by where they were born — far more reliably than they report flows, the year-by-year counts of who moved where. Guy Abel's 2013 method, refined in the Abel and Cohen 2019 release covering 200 countries, treats the change in these bilateral stock tables between two censuses as the net result of migration plus births and deaths, and solves for the smallest set of origin-to-destination flows that could have produced the observed change. The approach rests on demographic accounting: a stock at the end of a period equals the stock at the start, plus births into the group, minus deaths, plus arrivals, minus departures. By fixing the demographic margins and minimizing flows, it turns a fragmentary stock record into a complete, comparable flow table. This has become the standard way to build globally consistent five-year migration flow estimates where direct flow data simply do not exist.