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Background Notes


The reference period for the population estimates is mid-April of the years shown, while the migration flows are in respect of the twelve months to mid-April of the corresponding years, as are the births and deaths. The population classified by age and sex for the year 2011 is taken from the Census of Population.

Source of Migration data

The principal source of information for the estimation of the gross annual migration flows is the Quarterly National Household Survey (QNHS), which also provides the basis for the classification of the flows by sex, age group, origin/destination and nationality.

The migration estimates are compiled with reference to movements in other migration indicators such as the number of Personal Public Service (PPS) numbers allocated to non-Irish nationals and the number of visas issued to Irish nationals to a number of the destinations including Australia, US and Canada.  In addition, data on National Insurance numbers (equivalent to PPS numbers) issued to Irish nationals in the UK is referenced.

Calculation of annual population estimates

The annual population estimates for mid-April in this release were calculated by trending forwards the previous Census of Population data. For example, the base population data for estimating the April 2012 figure was the number of males and females in each region by single year of age and nationality as established by the 2011 Census. From this base, each person was aged by one year, births for the period were added and deaths were subtracted. 

The estimated number of immigrants was then added and the number of emigrants was subtracted. Allowance was also made for estimated inter-regional migration in arriving at the final 2012 figures. The end result of this overall process provided the population estimate for April 2012 which in turn will provide the base population for the subsequent year and so on. The population estimates are subject to revision once the definitive results of the next census become available.

The population by nationality estimates are made possible by trending forwards the previous Census of Population and incorporating gross migration flows by nationality based on responses in the QNHS. Births by nationality are estimated using the distribution of the nationality of babies as recorded in the 2011 census, while deaths by nationality are also estimated based on recent census results on the nationality distribution of the population by single year of age.

Migration classified by principal economic status and educational attainment

This release provides estimates of immigration and emigration by educational attainment (Table 5) and principal economic status (Table 6), based on responses in the QNHS.

The principal economic status question identifies whether the person sampled (who is aged 15 or over) is:

1. Working for payment or profit
2. Looking for first regular job
3. Unemployed, having lost or given up previous job
4. Actively looking for work after voluntary interruption of working life (for 12 months or more) for personal or domestic reasons     
5. Student or pupil
6. Engaged on home duties   
7. Retired from employment
8. Unable to work due to permanent sickness or disability
9. Other
This is a self-perception question, i.e. people are classified according to how they perceive their situation.  These categories are subsequently collapsed to provide the categories included in table 6.

As with all the breakdowns of migration (by age, nationality, origin and destination), the breakdown by educational attainment and principal economic status should be considered broadly indicative given the relatively small sample sizes associated with these flows. In addition, as a person’s principal economic status can change over the course of the year (and to a lesser extent their education attainment), for immigrants these two tables refer to their current status, while for emigrants these tables refer to their status in the period prior to departure.

This is part of the ongoing work by the CSO to improve data in this area, which in recent years has included new data on the nationality of emigrants (Table 2), the inclusion of Canada and Australia as individual countries of origin/destination in the migration estimates (Table 3) and an estimate of the total population by nationality (Table 9). 

Usual residence population concept

For the purpose of this release the population concept of usual residence has been used, i.e. all persons usually resident and present in the State on census night plus absent persons who are usually resident in Ireland but are temporarily away from home and outside the State on census night. All persons are classified according to their region of usual residence.