Regional Population Projections 2023-2042

Regional Population Projection Model

Demographic component method

The model used for these regional population projections is the Demographic Component Method which projects the 2022 usually resident (base) population forward under the chosen assumptions governing births, deaths and net migration.

The Demographic Component Method (DCM) works as follows:

1. Beginning with the first year after the base year, the usually resident population is aged one year using suitable survivorship ratios. The survivorship ratios reflect the underlying mortality assumptions determined by the Expert Group. This gives the Surviving Population. The same national rates are applied at a regional level.
2. Gross inward and outward migration rates that are expected to be experienced by the groups within the usually resident population are applied. The resulting estimate for net migration is then applied to provide the Surviving Population adjusted for net migration.
3. For females aged between 15-49, the assumed specific regional fertility rates are applied to calculate the assumed number of births in the year. The assumed infant mortality rates are then applied. By combining the adjusted number of births with the number of females and the number of males, the Total Projected Population for each year is obtained.
4. From the national projected population for each year, regional allocations of international and internal migration are applied. This provides the total projected population for each region for each year.
5. This process then continues for Base Year + 1, Base Year + 2 all the way to the end of the projection period (in this round of projections, 2042).

The following illustration shows this process as a flow chart.

Regional Limitations

Because of the greater uncertainty attached to regional as distinct from national population projections, the results for individual regions must be regarded as more provisional than national figures. The objective of the regional population projections is to determine how the population of the various regions would evolve in the period to 2042 if recent demographic trends were to continue, and are not forecasts.

Diagram of regional population projection model

Diagram of regional population projection model description

Classification of Regional Authority Areas

The Nomenclature of Territorial Units for Statistics (NUTS) were created by Eurostat in order to define territorial units for the production of regional statistics across the European Union. In 2003 the NUTS classification was established within a legal framework (Regulation (EC) No 1059/2003).

As the administrative territorial breakdown of EU Member States is the basis of the NUTS classification, changes made under the 2014 Local Government Act prompted a revision to the Irish NUTS-2 and NUTS-3 Regions. These changes included the amalgamation of the local authorities of Tipperary North and South, Limerick City and County Councils and Waterford City and County Councils. In addition three Regional Assemblies were established (Northern & Western, Southern, Eastern & Midland).

The main changes at NUTS-3 level are the transfer of South Tipperary from the South-East into the Mid-West NUTS-3 region and the movement of Louth from the Border to the Mid-East NUTS-3 Region. There are now three NUTS-2 Regions which correspond to the Regional Assemblies established in the 2014 Local Government Act and are groupings of the new NUTS-3 Regions. The revisions made to the NUTS boundaries have been given legal status under Commission Regulation (EU) 2016/2066. The new NUTS-2 and NUTS-3 structure and classification are displayed in the table below:

Concepts and Definitions

Usually resident population: All persons resident in the State, for a period that is, or is expected to be at least 12 months. Persons who are usually resident in Ireland but are temporarily away from home and outside the State on Census night are included in the usually resident population.

Age specific fertility rate: The age specific fertility rate for a particular age group is the number of live births to women in that age group per 1,000 females in the same age group.

Total fertility rate (TFR): The TFR represents the theoretical average number of children who would be born alive to a woman during her lifetime if she were to pass through her childbearing years (ages 15 - 49) conforming to the age specific fertility rates of a given year. The rate refers to a theoretical female cohort. The TFR is compiled by summing the age specific fertility rates for the relevant five-year age groups, dividing by 1,000 and multiplying by 5. The small number of births for which the age of the mother is not stated is distributed in proportion to the stated categories.

Life expectancy: The average number of additional years a person would live if current mortality trends were to continue. The expectation of life at birth represents the mean length of life of individuals who are subjected since birth to current mortality trends. Life expectancy is usually compiled on the basis of a life table showing the probability of dying at each age for a given population according to the age specific death rates prevailing in a given period.

Survivorship ratio: The survivorship ratio at age x, Sx, is calculated as Sx=Lx/Lx-1 where Lx is the population aged between x and x+1 assuming that 100,000 births occur each year according to the Life Tables.

Immigration: The action by which a person establishes his or her usual residence in the State for a period that is, or is expected to be, of at least 12 months, having previously been usually resident in another Member State or a third country.

Emigration: The action by which a person, having previously been usually resident in the State, ceases to have his or her usual residence in the State for a period that is, or is expected to be, of at least 12 months.

Net migration: The net effect of immigration and emigration. A positive entry denotes that inward migration exceeds outward migration and vice-versa.

Labour force participation rate: The number of persons at work or unemployed (either looking for first regular job or having lost or given up previous job) in a particular age group expressed as a percentage of all persons in that age group.

Young dependency ratio: The population aged 0 - 14 years expressed as a percentage of the population aged 15 - 64 years.

Old dependency ratio: The population aged 65 years and over expressed as a percentage of the population aged 15 - 64 years.

Total dependency ratio: The sum of the young and old dependency ratios.

Expert Group meetings

As in previous iterations of the projections, the CSO convened an Expert Group on Population Projections. The group met three times, on 3rd October 2024, 25th October 2024 and 15th November 2024 and agreed on the assumptions to be used in the projections. The CSO would like to thank all members of the group for participating in the projections process.

Expert Group membership

The Expert Group consisted of the following people: