1. Introduction

A census usually takes place once every ten years and is the largest and most complex statistical exercise undertaken in Northern Ireland. Census statistics are a vital source of information, and are widely used by government, public bodies, academia, commercial businesses and others to develop policies, allocate resources and help deliver services.

2. Purpose

The last census in Northern Ireland was taken on 21 March 2021. This report provides a factual account of how it was conducted and sets out a record of key elements associated with the operational delivery of the census. It is intended that this report will provide useful reference material to departments/agencies in major projects that require widespread engagement with the public and contain a significant digital element. This report will also help users of census statistics understand how those statistics were collected.

3. Impact of COVID-19

While some of the plans for the delivery of the census had to be changed due to the pandemic, this report does not detail these changes, but rather outlines what actually happened. However, it is important to recognise, whilst reading this report, the challenge of undertaking census data collection during the pandemic.

4. Roles and responsibilities

Census Office, part of the Northern Ireland Statistics and Research Agency, an executive agency within the Department of Finance, has responsibility for delivering the census in Northern Ireland. Census Office staff worked closely with colleagues from the Office for National Statistics (ONS) in England and Wales on all aspects of the census operation.

In addition, Census Office staff worked with colleagues from within the Department of Finance, and across the Civil Service, as well as organisations from the public, private and voluntary sectors. A wide range of external suppliers were also key to the successful delivery of the census operation, and these are listed at Appendix A. The input and assistance of all stakeholders, suppliers and contributors to Census 2021 is noted and appreciated.

5. Definitions

A list of the terms and definitions unique to census operations can be found at Appendix B.

6. Operational areas

6.1. Stakeholder engagement and communications

The Stakeholder Engagement and Communication (SEaC) team within Census Office was responsible for the development, implementation, management and delivery of communications and public engagement for Census 2021. In undertaking this work, two overarching aims were critical:

• to educate the population on the value of the census and its importance;

• to explain and advertise the ways to make a census return, in order to make it easier for everyone to participate.

These were underpinned by a series of key objectives, one of which was ‘to promote a digital first approach’.


6.1.1. Advertising

From the outset, Census Office recognised the importance, not just of raising awareness of the census, but also of highlighting the benefits of completion. In partnership with the Government Advertising Unit, Census Office implemented a full advertising campaign, using a wide range of approaches, including TV, radio, press, digital and outdoor. This advertising and the communications approach contributed to increased awareness of the census from 70% in 2019 to 99% by 2021. The campaign had five phases, and contained key messaging with changes in focus as follows:

Table 1: Census 2021 advertising phases
Phase Objective Date from Date to
1 Awareness: The census is coming 22-Feb 05-Mar
2 Motivation: The census is almost here 06-Mar 18-Mar
3 Act now: Census is here 16-Mar 21-Mar
4 Reminder: There’s still time to complete your census 22-Mar 11-Apr
5 Obligation: Complete it now 12-Apr onwards


6.1.2. Stakeholder engagement

Census Office developed a comprehensive database of stakeholders, including groups and organisations across Northern Ireland – local councils, the police, political parties, public representatives, schools, churches, large employers and voluntary groups. Prior to and through the operational data collection period, Census Office worked closely with these stakeholders, to promote, raise awareness and highlight the benefits of completing the census. Census Office also developed a database of local stakeholders for each council area, to help facilitate Census Area Managers (CAMs) in their engagement with community groups.

A range of posters and leaflets were printed and circulated to stakeholders, with a view to displaying within their premises (for example, in COVID-19 vaccination centres). Other promotional material was also provided to schools and other groups. Not surprisingly, due to COVID-19 restrictions the vast majority of stakeholder engagement was carried out online.


6.1.3. Schools

A dedicated schools programme entitled ‘Let’s Count’ was developed in partnership with the Council for the Curriculum, Examinations & Assessment (CCEA). Its aim was to inform children about the census, contribute to their learning and use the power of children to get adults in their households to fill out the census form. The pupil resources were made available at CCEA Let’s Count. There were more than 9,000 views of the Census at Schools pages. The programme was impacted by the pandemic with schools being closed and home schooling in place. However, the resources were communicated to primary school teachers through a series of targeted mail drops, social media posts and an item on the education communications network news desk.


6.1.4. Communication

At the start of the census collection period, a press conference was held and a number of press releases were published throughout the operational period. The assistance of the local media throughout the census is noted. The census was also running in England and Wales at the same time as Northern Ireland, and although Northern Ireland had its own communications plan, there was a natural overlap, with the underlying message around the census being reinforced.

Key communication features included the Census NI website, social media @NICensus2021 and the call centre (0800 328 2021). These resources were kept up to date with relevant and timely information. The new social media channels (Facebook and Twitter) were vital in posting regular updates and reinforcing key messages. All of this activity had the primary aim of encouraging the public to complete their census return (see Appendix C for social media and website activity).


6.1.5. Printing and digital products

Census Office developed a co-ordinated and controlled list of public products (for example, leaflets, letters etc.). This was managed centrally to ensure consistency of presentation and tone, and to provide a record of all printed and digital products used in connection with the census.


6.1.6. Accessibility

One of the keys to a successful census was ensuring that the completion process was easily accessible to all. This included making available a range of accessibility products, the aim of which was to provide help and guidance.

Accessibility products in large print, Easy Read, Braille, as well as British and Irish Sign language were produced. This guidance was primarily to help respondents understand the census questions and then complete the questionnaire.

Accessibility products were available to download from the Census NI website, or upon request from the contact centre.

6.2. Address register

Central to the operational design of Census 2021 was the development of a comprehensive address register, essentially a database of all addresses in Northern Ireland (households and communal establishments).
The address register was a key tool in guiding census data collection and four key functions stemmed from it:

  1. to facilitate the posting out of letters/forms to households and communal establishments;
  2. to facilitate the process for following up non-responders by identifying addresses for which no return had been received;
  3. to provide address ‘lookups’, for the online questionnaire, to facilitate responses to address questions. The whole address register was used for this aspect and included invalid addresses for example, derelict, demolished and non-residential/commercial addresses to aid completion of questions like ‘address 1 year ago’ and ‘workplace address’;
  4. to assist with the ‘address resolution’ function. This function managed the validation of new addresses added to the register, and the process for switching off addresses identified as invalid by census field staff.

6.3. Data collection services

A major focus of Census Office in the run-up to Census 2021 was developing the systems and services required to collect data securely and efficiently from the general public. In Census Office this was managed through the Data Collection Services (DCS) team. This team worked closely with colleagues in ONS and through a range of external suppliers of services.

The main areas and processes delivered included:

• Print and post out (PPO) – the management of the printing and posting out of all initial contact letters (675k), reminder letters (250k), door-drop postcards (c.2.5m) and all materials requested by the public during the operation (samples of some of the various communications can be found at Appendix D);

• Electronic questionnaire (eQ) – this involved the delivery of Northern Ireland specific questionnaires (both through ONS managed systems and through local systems developed for communal establishments). As the eQ was the main public facing element of the census data collection process, a significant amount of time was taken for the design of the system and subsequent testing. This system was developed in-house by ONS working closely with Census Office staff, and was a key success element of the census. Whilst the eQ system was initially developed prior to the pandemic, a number of updates to improve user experience were required at a late stage. This requirement, primarily due to the impact of the pandemic, brought significant challenges to the delivery timeline;

• Questionnaire management (QM) – print and post out of initial contact paper questionnaires (168k), reminder paper questionnaires (80k) and questionnaires requested by the public during the operation (50k). This service included the post-collection scanning of all returned paper questionnaires, capture of raw data from paper questionnaires and statistical coding of both the paper and online returns;

• Paper questionnaire return service (PQRS) – receipting of all returned paper questionnaires and transmission of this receipting information to the central response management system. This service also included delivery of physical questionnaire packs to the data capture centre;

• Contact centre/online help – supporting the public with making their census returns required the design, development and delivery of content and requirements for the contact centre and online help. In total 161,616 phone calls were received by the contact centre – details are shown at Appendix E. Census Office staff developed all the Northern Ireland materials and managed/trained the relevant staff in the delivery of these services;

• Response management – this was a central technology system for the management of data collection developed and managed in-house by ONS. The system allowed live tracking of the status of each census return and of interactions/requests with addresses/householders throughout the operation. This system acted as the basis for management information and informed the decision making process around changes to the interaction with householders during the collection period. In particular, the management information helped inform key decisions in relation to reminder letters and ‘field-work’.

The remainder of this section gives some further information on the level of utilisation of these key services.


6.3.1. Contact centre

• The centre opened for telephone calls from 1 March 2021. The opening hours were 8am to 8pm Monday to Friday (excluding bank holidays), Saturday 8am to 1pm, and 8am to 8pm over census weekend (20 and 21 March 2021). The contact centre provided support and information using various methods, including webchat, webmail, telephone, SMS, online help and an interpretation service via a dedicated language line;

• The contact centre handled a wide range of enquiries, providing help to complete census for households, individuals, visitors, vacant properties or holiday homes, as well as requests for paper questionnaires (PQs), individual forms, continuation forms, large print PQs, Braille and translation booklets. The contact centre service also facilitated householders who wished to complete their census over the phone;

• In total the contact centre dealt with 161,616 calls up to 8 July 2021.


6.3.2. Postal delivery of wave of contact materials

• Pre-delivery postcards were issued to all addresses from Monday 22 February 2021;

• Initial contact paper questionnaires (PQ) (168,000) were issued to a range of addresses across Northern Ireland between 1 and 2 March 2021;

• Initial contact letters (invitation to take part online) (675,000) were issued to the remaining addresses between 3 and 5 March 2021;

• Pre-census day postcards were delivered to all addresses from Monday 15 March 2021;

• Post-census day thank you/reminder postcards were issued to all addresses from Monday 22 March 2021;

• First targeted reminder letter was sent to all non-responders for whom (at 25 March) Census Office had no evidence of a response. This letter landed with 190,000 addresses from Wednesday 31 March 2021;

• Second targeted reminder which included a paper questionnaire to all non-responders for whom (at 13 April) Census Office had no evidence of a response. In total paper questionnaires were issued to 79,000 addresses – the questionnaires landed from Monday 19 April 2021;

• Third and final targeted reminder letter was issued to all non-responders for whom (at 5 May) Census Office had no evidence of a response. In total the reminder was sent to 60,000 addresses – the letter landed from Monday 10 May 2021.


6.3.3. Online system: the electronic questionnaire

• It should be noted that the online system was designed in line with Government Digital Services (GDS) standards which ensured that it could be used by as many people as possible. This allowed people, for example, to use speech recognition software or use the website with a screen reader;

• The online system for the electronic questionnaire (eQ) went ‘live’ with a ‘soft launch’ on 23 February 2021 and ‘officially launched’ on Monday 1 March 2021. The system was designed to be accessed on a variety of technology such as laptops, mobile phones, tablets, personal computers, TVs etc., using a wide range of web browsing software;

• In total, 49% of online returns were completed on a mobile phone, 42% on a personal computer/laptop and 9% on a tablet computer;

• The online system offered the public the option to request that access codes be sent via text message to their mobile phone. This facilitated access to the online questionnaire and this process also supported the receipt of a confirmation e-mail. The system also provided online help with specific information available in up to 17 languages. In addition, there was dedicated help for people covering a wide range of issues, including students, vacant properties and holiday homes;

• The online system for data collection was available from Tuesday 23 February 2021 until Monday 24 May 2021 at 8pm (a period of 13 weeks).

Details of census returns during the operational period, including a breakdown of online/paper questionnaires and dates/times of completion can be found at Appendix F.

Further information on the digital services of the census and their design may be found on the Office for National Statistics website at Delivering the Census 2021 digital service.

6.4. Field operations

A final element in collection was a targeted ‘push’ on the doorstep of non-responders. This required the hiring of a team of almost 1,900 field staff (one enumerator for each of the 1,676 enumeration districts (EDs) plus managers). The main purpose was to visit properties for which no census questionnaire had been returned and, if possible, contact the householder and remind them of their legal obligation.

Field staff were managed by the field operations team within Census Office. To create the field team a recruitment campaign was launched in mid-2020 and staff recruited at three grades, 12 Census Area Managers (CAMs), 174 Census Team Co-ordinators (CTCs) and 1,676 Enumerators. Pressure on the timetable, largely due to the pandemic, resulted in only 1,530 enumerators taking up employment. This shortfall in numbers was covered by some enumerators taking on an additional enumeration district.

All field staff were provided with the necessary training and equipment. This included a smartphone, which enabled enumerators to manage their workload, as well as acting as both a communication and safety device. Enumerators accessed their daily workload through an application developed by TotalMobile, a local company. This application provided a list of non-responding addresses to ‘follow-up’.


6.4.1. Follow-up

Following up with non-responding households was important in increasing the return rate. A strategic approach was adopted. For example, in student areas ‘student specific’ postcards were delivered by enumerators during the ‘soft’ follow-up period (see below).

While census day was 21 March 2021, enumerators only started the ‘soft’ follow-up phase by visiting non-responding addresses from 26 March 2021. During the ‘soft’ follow-up enumerators assessed non-responding properties and, where necessary, delivered a targeted postcard indicating that no response had been received. Due to COVID-19 restrictions, there was no direct engagement with householders during this ‘soft’ follow-up phase.

Given the Easter holidays and the desire to allow the first posted reminder letters to have an impact, a pause in field operations ran from 2 – 7 April, with the regular follow-up period starting on 8 April. Details of follow-up phases are shown below:

Table 2: Census 2021 follow-up phases
Phase Date from Date to Objective
1 26-Mar 01-Apr Soft follow-up
1 (cont.) 08-Apr 18-Apr Regular follow-up
2 19-Apr 25-Apr Regular follow-up
3 26-Apr 02-May Regular follow-up
4 03-May 09-May Regular follow-up

The regular follow-up period, during which enumerators ‘knocked on doors’ in an attempt to make contact with the householder, ran from 8 April until 9 May. In total 375,286 visits were carried out by enumerators during the follow-up period, full details of visits and return rates can be found at Appendix G.

6.5. Operational period

To run Census 2021 required consultation, legislation and the development of a host of operational plans. However, the main operational data collection period was short, running for 13 weeks from 23 February to 24 May 2021. It can be defined broadly as the ‘data collection’ phase either side of census day. The key milestones are shown in the diagram below: