The CSO said that the figures published today (24 June) are part of the CSO Frontier Series, which may use methods that are under development and/or data sources that may be incomplete.
Attributes available from census data, such as religion or health status, are not available from administrative data, and some datasets lack geographical detail.
Official population estimates are currently based on the census of population and population-and-migration estimates.
This report focuses on activity in administrative data, where engagement with the administrative system is taken as an indication of residence in Ireland.
This publication attempts to count the ‘usually resident’ population of Ireland in April 2022, or those who have lived in the country for a continuous period of at least 12 months, including that month.
Usual residence is a widely used statistical concept, recognised by many international bodies, including the EU.
Usual residence can be inferred by looking at the level of activity in different administrative-data sources over a period of time.
The CSO says that there are challenges with both methods of defining usual residence. For example, in the census, respondents may misinterpret the question, while in administratively sourced population estimates there will often be coverage issues in individual administrative datasets and definitional issues.
Changing birth rate
The age structure of the population reflects the impact of changing birth rate and migration patterns over recent decades, the CSO has said.
Cathal Doherty (statistician in the life events and demography section) said that the experimental methodology is not comparable with official CSO population estimates such as census data.
“This research paper is intended to both illustrate the potential of administrative data to produce demographic statistics and highlight the challenges that arise,” he said.
While administrative datasets are designed for the operational needs of Irish public bodies, and not as statistical data sources, it is generally accepted that the activity of individuals in such datasets can be used to indicate their presence in Ireland.
More countries are moving towards greater use of administrative data in censuses, a move supported by United Nations Economic Commission for Europe (UNECE) recommendations.
The benefits of using administrative data sources include reduced cost, reduced burden on respondents, improved timeliness, and greater frequency of results.
The Census of Ireland has been postponed twice in recent years, due foot-and-mouth disease in 2001 and the pandemic in 2020.
Robust data
Robust administrative population data available on an annual basis would offset some of the risk of an information deficit and insulate users from such delays and postponements, the CSO said.
Some aspects of using administrative sources for counting the population will require further development –including the relatively limited range of variables available (commuting patterns, use of Irish language, religion), from administrative sources compared with the census, and the production of statistics at small geographic areas.
The CSO's access to public-sector data flows will help with both issues, as will the increased collection of Eircodes with the move to online public administration of services.
The CSO has said that it is committed to addressing these issues in partnership with public-sector bodies and will work towards improving these estimates based on data improvements.
Metrics
The key metrics in assessing these data improvements for the population count are the percentage of records with Eircodes (currently above 90%) and the percentage of records coming from ‘real-time’ sources (approximately 70%), where the activity recorded is from a recent time period.
The CSO said that it could measure activity only in the available administrative sources. Those who did not have any interaction with the State during the reference period applied by the rules would not be included in the population estimates.