2019 report: Accuracy and completeness of the 2018 electoral registers in Northern Ireland


We run accuracy and completeness studies to measure the quality of the electoral registers, and to assess how this changes in response to legislative developments, administrative and population changes.

The quality of the electoral registers is measured in two main ways: their accuracy and their completeness.

The results for Northern Ireland in December 2018 show that:

  • the parliamentary register was 74% complete and 80% accurate
  • the local government register was 73% complete and 80% accurate

This research leads to an estimate of between 360,000 and 430,000 people in Northern Ireland who were eligible to be on the local government register but were not correctly registered.

It also shows that there were an estimated 230,000 to 285,000 inaccurate entries on the local government register in December 2018 (out of a total of 1,281,576 entries).

Our study on the accuracy and completeness of the electoral registers in December 2015 found the parliamentary register in Northern Ireland was 81% complete and 87% accurate and the local government register was 79% complete and 87% accurate.

The figures for 2018 show a return to the levels of accuracy and completeness recorded in 2012, when completeness of the local government register was 71% and accuracy was 78%.

There is a canvass of electors in Northern Ireland scheduled for 2020. This is a timely opportunity to improve the quality of the registers. However, we believe that more could and should be done to modernise the registration system in Northern Ireland, as in Great Britain, to ensure that the registers remain as accurate and complete as possible in the period between canvasses.

What we mean by accuracy and completeness

By accuracy we mean that ‘there are no false entries on the electoral registers’. Accuracy is therefore the measure of the percentage of entries on the registers which relate to verified and eligible voters who are resident at that address. Inaccurate register entries may relate to entries which have become redundant (for example, due to home movement), which are ineligible and have been included unintentionally, or which are fraudulent. 

By completeness, we mean that ‘every person who is entitled to have an entry on an electoral register is registered’. Completeness refers to the percentage of eligible people who are registered at their current address. The proportion of eligible people who are not included on the register at their current address constitutes the rate of under-registration.

The study of the 2018 December register is our latest in Northern Ireland since December 2015. When considering these findings it is important to note that the last electoral event before this study was in June 2017 and that this study does not account for changes to the register made in the period leading up to the May 2019 local and European Parliamentary elections in Northern Ireland.

There has also not been a canvass in Northern Ireland since 2013, although the next canvass is scheduled for 2020.