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Introduction and Assumptions

Introduction and Summary of Assumptions

CSO statistical release, , 11am

Introduction and recent regional population trends

This report provides population projections for the 8 Nomenclature of Territorial Units for Statistics (NUTS) NUTS-3 Regional Authority Areas classified by age and sex for the period 2023 - 2042. The usual resident population estimate based on Census 2022 (5,183,966 persons) provides the base for these projections. 

Figure 1.1 and Table 1.1 show how the population of the 8 NUTS-3 Regional Authority Areas has evolved over the period 2016 – 2022. Since 2016, all regions have shown some level of population growth. The Mid-East and Dublin regions have seen the largest population increases of 83,100 (12%) and 132,500 (9.9%) persons respectively from 2016 to 2022. The Midland has seen the smallest increase with a total growth of 26,900 (9.2%) people over the period. Similarly, the Border region has seen the smallest percentage increase of 7.3% (28,900 persons) over the same period.

Figure 1.1 Estimated Regional Population, 2016 - 2022
Table 1.1 Actual population of NUTS-3 Regions, 2016 - 2022

Regional Population Projections model

The model used for these projections is similar to that used in previous CSO Projection Series, namely the demographic component method (see Background Notes). This approach involves projecting the Census 2022 usually resident NUTS-3 population forward under the chosen assumptions relating to future trends in fertility, mortality, international migration and internal migration. One set of assumptions was chosen for fertility, one for mortality, one for internal migration and three for international migration up to the year 2042, giving three sets of results altogether.

The regional population projections contained in this release represent a top-down disaggregation of the national projections published in July 2024. The assumptions used in the national model (fertility, mortality and international migration) are regionalised, where suitable, mainly based on recent historical data. In addition, internal migration between regions is also examined and applied for the regional projections. The outcome of this procedure is a set of regional population projections based on what would be likely to happen if recent trends in fertility, mortality, international and internal migration were to continue, subject to the overall constraint of the national population projections. This report is not an attempt to predict the future but rather presents how the population could evolve under different scenarios.

The most up-to-date information available was used in preparing the projections including the results of Census 2022, information on births and deaths up to Q2 2022 and results of the Q2 2022 Labour Force Survey (LFS). Population and migration estimates for 2023 and 2024 were also examined.

The assumptions were agreed by an Expert Group (see membership in Background Notes) which met during the period October 2024 to November 2024. The Central Statistics Office is grateful to the members of the Group for their input and advice during the discussions leading to the adoption of these assumptions.

The assumptions underpinning the regional population projections are outlined below. The following chapter of this report then describes the regional population projections results.

Summary of assumptions agreed

The assumptions agreed by the Expert Group to project the regional population forward from 2022 to 2042 are summarised below: 

Fertility Assumptions Agreed

Total fertility rate to decrease from 1.55 to 1.3 by 2037 and to remain constant thereafter to 2042.

Mortality Assumptions Agreed

Mortality rates for males and females are both assumed to improve at 2.5% per annum to 2042.

These rates are assumed to apply to all ages up to age 90.

These assumptions will result in gains in life expectancy from:

  • 80.2 years in 2022 to 84.2 years in 2042 for males.
  • 83.9 years in 2022 to 87.4 years in 2042 for females.

The same approach has been applied in the national projections.

International Migration Assumptions Agreed

Three international migration scenarios were taken into consideration by the expert group:

M1: Net migration starting at +75,000 in 2022 and decreasing incrementally to +45,000 per annum by 2027 and remaining at this level to 2042.
M2: Net migration starting at +75,000 in 2022 and decreasing incrementally to +30,000 per annum by 2032 and remaining at this level to 2042.
M3: Net migration starting at +75,000 in 2022 and decreasing incrementally to +10,000 per annum by 2032 and remaining at this level to 2042.

Internal Migration Assumptions Agreed

Internal migration between NUTS-3 regions will remain in-line with Census 2016 and Census 2022 levels.

Fertility assumption

Fertility assumptions were agreed to start with a national TFR of 1.55 in 2022 and decrease to 1.3 by 2037 and remain constant thereafter. This assumption, which remains in line with the national projections, was decided by taking the following points into consideration:

  • Births have declined almost consistently since 2009, with fewer than 60,580 and 54,490 births recorded in 2021 and 2022 respectively. The provisional number of births for 2023 stands at approximately 54,650.
  • Age specific fertility rates have been declining across most age groups in recent years (See Table 1.2).
  • Decline in the number of women of childbearing age. Not only are the age specific fertility levels declining, but the number of women in the younger age groups is also falling. For example, the number of women aged 20 - 29 has been in decline in recent years, falling from 383,000 in 2009 to nearly 304,000 in 2022 (-20.6%), while the number of women aged 30 - 39 has remained almost static, with small fluctuations between 368,000 and 385,000 since 2012. This can be compared to the period between 1991 and 2008 when the number of women aged 20 - 29 grew by almost 135,000 (52.7%) and the number of women aged 30 - 39 increased by 108,500 (44.3%). The combination of declining fertility rates allied with a decrease in the number of women of childbearing age has resulted in the fertility rate falling from 2.10 in 2010 to 1.53 in 2022 or a decline of 27.1%. 
  • The average age of first time mothers increasing. There has been an increasing trend towards later births, with the average age of first-time mothers rising by 7.2 years from 26 years in 1985 to 33.2 years in 2022.

These age specific fertility rates and TFRs will be applied to each NUTS-3 region separately in the calculation of these projections (See Figure 1.2 and Table 1.3).

Table 1.2 Age specific and total fertility rates, 2000 - 2022

Figure 1.2 Regional Total Fertility Rates, 2021 and 2022
Table 1.3 Projected Total Fertility Rates for NUTS-3 Regions, 2022 - 2042

Mortality assumptions

There is a general consensus internationally among demographers that improvements in life expectancy will continue for the foreseeable future. The main question that was addressed in the national projection series by the Expert Group was the rate of improvement. The Expert Group continues to be indebted to Dr Rabia Naqvi and Dr Linda Daly of UCC School of Mathematical Sciences, Professor Shane Whelan of UCD School of Mathematics and Statistics, Dr Mary Hall of DCU School of Mathematical Sciences and Mr Niall Quinn, of the Society of Actuaries in Ireland, for their input and expert guidance with regards to the mortality part of the national projections, which forms the basis of regional mortality assumptions.

The agreed mortality assumptions, which are taken in-line with the national projections, are outlined below:

Mortality rates for males and females are both assumed to improve at 2.5% per annum in the short-term over the course of these projections. The long-term rate of improvement is assumed to be 1.5% per annum. The short-term rate declines linearly over a 25 year period to the long-term rate. These rates are assumed to apply to all ages up to age 90.

These assumptions will result in gains in life expectancy from:

  • 80.2 years in 2022 to 84.2 years in 2042 for males.
  • 83.9 years in 2022 to 87.4 years in 2042 for females.

There is no regional variation applied to the mortality assumptions. While consideration was given to examining the use of Regional Life Tables for this exercise it was decided to use the national mortality assumption across the regions given the relatively small number of deaths in some regions, combined with the relatively small impact of regional differentials in the number of deaths.

International migration assumptions

The regional population projections will follow the same 3 international migration scenarios that were considered in the national Population and Labour Force Projections release, namely:

M1: Net migration starting at +75,000 in 2022 and decreasing incrementally to +45,000 per annum by 2027 and remaining at this level to 2042.
M2: Net migration starting at +75,000 in 2022 and decreasing incrementally to +30,000 per annum by 2032 and remaining at this level to 2042.
M3: Net migration starting at +75,000 in 2022 and decreasing incrementally to +10,000 per annum by 2032 and remaining at this level to 2042.

The application at regional level involves allocating levels of international migration to each region under low, medium, and high international migration. This is done using patterns observed in the Labour Force Survey for the period 2017-2022. Flows were also broken down by single year of age and gender on the same basis as for the total flows into and out of the State (i.e. no region-specific age distribution has been applied). 

Figure 1.3 State-level intercensal annual average international migration, 2022 - 2042

Internal migration assumptions

By examining a person’s usual residence at the time of a census and one year previously it is possible to determine inter-regional migration patterns. An analysis of the data from the 2016 and 2022 Censuses for internal migration between regions reveals a fairly stable picture in terms of the magnitude of the inward, outward and net migration flows. The 2016 and 2022 Censuses showed Dublin experiencing net outflows of 4,400 and 4,780 persons respectively in the year to April 2016, with the Mid-East region being the primary beneficiary both years.

Following close consideration of the various internal migration flows, the Expert Group agreed that internal migration in Ireland tends to be relatively stable and that the 2016 and 2022 numbers represent very well current internal migration patterns including such questions as work from home. The Expert Group agreed with the proposal to use the average of 2016 & 2022 internal migration patterns to use in projecting the regional population forward to 2042. 

Figure 1.4 Annual inter-regional net migration, 2022 - 2042

Data availability

While this report contains a number of summary tables, detailed results of the population projections classified by sex and single year of age for each year from 2022 to 2042 are available on the CSO Statistics Database.

The detailed projections are provided for the three different migration assumptions distinguished in the publication i.e. M1, M2 and M3. Data on births, deaths and net migration classified by sex are also available for each year from 2022 to 2042.