Estimation of Emigration from the United States using International Data Sources

1. Estimation of Emigration from the United States using International Data Sources Jason P. Schachter Senior Statistician, Bureau of Statistics, ILO Geneva United Nations Expert Group Meeting on Migration Statistics New York, NY, December 4-7, 2006

2. Introduction • Many countries, including US, do not collect emigration data. • Needed for the estimation of net international migration. • Too problematic and expensive to collect information on US citizens living abroad. • Attempt to use international data sources to estimate number of US born/citizens moving abroad.

3. How many US citizens live abroad? • State Department’s estimate was 4.1 million in 1999. • One-quarter (1 million) in Mexico, 700,000 in Canada. Top 10 countries had 70% of all US citizens living abroad • Huge discrepancies in totals when compared to international data sources, though similar country rankings. • State Department estimates appear to be two to three times larger then international data sources (closer to 1.5 to 2 million).

5. About State Department data • State Department figures are “best guess” estimates • Voluntary registered + an estimated number of non-registered • Purpose of data is in case of an emergency evacuation, not to reflect exact numbers. Their accuracy is of low priority to the State Department • Overestimation also possible due to failure to deregister, as well as registration for short stays abroad (compared to “usual residents” in other data sources)

6. US military abroad • Inclusion or exclusion of US military personnel from data sources adds to difficulties • According to pre-2001 military base report, one-quarter million officially reported, plus an equal number of dependents. • True size not reported for “security” reasons. • Does not include military stationed in Afghanistan and Iraq, among other places. • Not normally included in foreign data (due to universe coverage, residency rules), but US military, support staff, and dependents living off-base could be included. • Needs to be kept in mind when estimating number of US abroad

7. Using international stock data to estimate “net migration” • Purpose of exercise was to investigate the feasibility of using international data sources to estimate the number of US citizens moving abroad • Requested data on US citizens and/or US born from the two most recent Censuses of 5 countries: Canada, France, Italy, Poland, and the United Kingdom. (UNECE/EUROSTAT data exchange initiative) • A number of measurement/data comparability issues need to be kept in mind

8. US Citizens vs. US Born • By US law, US born is synonymous with US citizenship • Not treated as such in international data sources (self-reported) • For example, 2001 Spanish Census counted 21,000 US born in US. 12,000 were foreigners, while 9,000 were Spanish. • Dual “US-other” citizens usually not counted as US citizens while living abroad (and only some countries -Austria, Canada, Greece, Ireland, Japan, Malta, Portugal, Switzerland, and most of Eastern Europe –collect this information on their Censuses) • Conversely, limiting definition to US born misses US citizens born abroad of American parents or naturalized US citizens

9. Other measurement issues –data comparability • Comparability between different data sources (Census, registers, other administrative records, border crossings). • Limit analysis to Census “stock” data to reduce data comparability issues. No “flow” data. • Data quality --sampling and measurement error-- Did not evaluate quality of data sources. • Different universes included in data sets, e.g. usual residence definitions (de jure vs. de facto), how treat those living temporarily abroad (e.g. students) • Need consistent universes between data sources (over time within country, and between countries)

10. Country results • Requested the age and sex distribution of enumerated US citizens and/or US born from the two most recent Censuses. • France, Italy, and Canada asked both country of birth and citizenship on their two most recent censuses • UK only asked country of birth • Poland collected this information on its 2002 Census, but not on its 1988 Census, so not able to estimate • Only Canada and Poland collect information on dual citizens (though not able to release Canada’s results due to confidentiality restrictions)

12. Estimation uses a “crude” residual methodology (in brief) • Observe stock data at two points in time (T1 and T2) from similar sources (e.g. Census) • Survive T1 population to T2 (using age and sex specific death rates), for which there is a comparable observed population. Difference between the survived and observed population is “net migration.”

13. Estimation Methodology (in more detail) • From two most recent Censuses, establish a T1 (circa 1990 Census) population of US born and/or citizens, and a similar T2 (circa 2000 Census) observed population. • US born: T1 population is survived (using age and sex specific death rates based on the resident US population for the T1 year) a number of years equal to the difference between T1 and T2. • The difference between the survived T1 and observed T2 population is assumed to measure “net international migration” between the US and that given country over the T2-T1 time period. • This figure is then divided by the time period to yield an average annual net migration figure

14. Estimation Methodology (cont.) • Used same methodology for US citizens, but need two additional components: birth of children to US female citizens (added to the survived T1 total) and US citizens who naturalized to another country –and revoked their US citizenship-- (subtracted from the survived T1 total). • Proved difficult to incorporate additional components. • The number of births to US females is not necessarily equal to a number of new US citizens (also misses potential births to non-US nationals married to US males). • Not able to find any public records on number of US citizens who naturalized in these countries.

15. Method makes some dangerous assumptions • The US population living abroad has the same age and sex-specific death and birth rates as the US resident population • Needed to make assumptions about the age distribution of Americans living abroad (people were equally distributed within each age cohort) • Improved coverage (measurement) of foreigners/foreign-born from one Census to next might be the actual reason for apparent “net migration gain” • Measurement error around figures, from sample based data, could be resulting in “net migration.”

16. (An even cruder) estimate of flows to and from specific countries • Calculated a rough estimate of the in-flow of US born/citizens to the US from specific countries, using the US Census 2000 residence 5 years ago question, and dividing by five. • Then used our net migration estimate combined with the in-flow estimate to calculate an out-flow estimate. • Problems: US Census could include different universes than other countries (e.g. students and military) • A five-year flow divided by five is not equivalent to a one-year flow (migrants could have returned at any time during the 5 year period, migrants could have left and returned between 1996 and 2000, or they could have moved to multiple countries during the 5 year period), all of which underestimates the true size of country-specific flows. • Despite these problems, it is our best guess estimate of flows to and from these countries.

18. Evaluation • Net migration results looked OK (at face validity, given there are no sources to compare). • Canada and Great Britain had roughly the same size of flows and net, despite a larger stock population in Canada? • Large number of dual-nationals in Poland (30,000 vs. 1,000 US citizens). • US born easier to calculate than US citizens (dual citizen problem, components needed to survive population) ---however citizenship data are more readily available from different sources

19. Conclusions • How to deal with US military and dependents • Data quality issues—need to evaluate international sources • Is this method possible combining different data sources (Census, house hold surveys, population registers, etc.)? • Reliability of method is questionable, since it could mask fluctuations over time. • Recommend using US born data to calculate • Recommend expanding project to include top thirty receiving countries –but special tabulations from these countries will be needed-

20. Contact Information Jason Schachter, Ph.D Bureau of Statistics, Room 5-51 4, Route des Morillons CH-1211 Geneva, Switzerland Phone: +41 (0)22 799 6954 E-mail: g1stat@ilo.org