1. Executive summary

In December 2018, the government presented to Parliament a White Paper Help Shape our Future: The 2021 Census of Population and Housing in England and Wales (PDF, 967KB). This outlined the Office for National Statistics' (ONS) proposal for the enumeration base to remain the same for Census 2021 as for the 2011 Census. This maintains continuity and means that we will continue to collect information on:

  • usual residents of the UK

  • census short-term UK residents

  • overnight visitors

Definitions for these groups can be found in Outputs and enumeration bases: residential address and population definitions for Census 2021. The remainder of this report discusses usual residents of the UK and Census short-term UK visitors together as "residents" for brevity as this report focusses on the division between these two groups and visitors. Identification of census short-term UK residents takes place in the migration questions, as described in the report Second address, migration and citizenship question development for Census 2021.

Census 2021 will be an online-first census, with a target of 75% online returns. Implementation of the correct enumeration base on the electronic questionnaire is crucial for the 2021 Census to be successful.

On paper, we recommend using the 2011 Census questions on counting residents and visitors in households as it was a successful design and ensures consistency with prior censuses.

Online, we will collect resident and visitor data in a way that meets Government Digital Service (GDS) Standards for the online questionnaire for Census 2021. As such, the structure of how this information is collected has changed. The overall user journey for the collection of names of residents is:

  • questions about if the respondent is resident at the address and their name

  • a question on the types of resident at the address

  • questions about the names of other residents, collecting one name at a time

  • a check of the count of residents to confirm that those temporarily away, or temporarily staying have been remembered

  • a question on the types of overnight visitor staying on Census night

  • questions about the names of overnight visitors, collecting one name at a time

  • a summary of the information provided

The paper and online forms collect the same information, the names of all residents and all visitors, using questions optimised for the mode of completion.

Residents are asked individual questions on housing, citizenship, migration, second addresses, socio-demographic topics, qualifications, labour market and employment. Reports on these question topics can be found on the Question development pages.

For residents, a write-in box to capture middle names has been added on both paper and online questionnaires.

Overnight visitors are asked for name, date of birth, sex, and usual address only. They are not asked for middle name.

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2. Aim of question development report

Since the publication of the White Paper, the Office for National Statistics (ONS) has conducted and concluded the final phase of testing on counting residents and visitors.

This report provides links to previously published research and the findings of additional testing that led to the final recommended questions for Census 2021 in England and Wales. The questions and response options for Census 2021 have now been finalised through the census secondary legislation: the Census (England and Wales) Order 2020, and Census Regulations for England and for Wales.

The evidence base for the design used in the 2019 Rehearsal is included in the section Research that led to the 2019 Rehearsal question design. The evidence base for the finalisation of the questions for Census 2021 is discussed in the section Research that led to the recommended Census 2021 question design.

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3. Research and development timeline

In June 2015, the Office for National Statistics (ONS) held a formal, 12-week consultation process asking census users for their views on the topics that were required in the questionnaire in England and Wales. The aim of the consultation was to promote discussion and encourage the development of strong cases for topics to be included in Census 2021.

In May 2016, the ONS published its response to the 2021 Census topic consultation. This set out our updated view on the topics to be included in Census 2021, including:

  • a summary of proposals for new topics
  • next steps
  • an overview of our plans

The 2021 Census topic consultation revealed a clear requirement to count and record household residents and visitors using the same definitions as in 2011. A detailed summary of the consultation responses relating to this topic can be found in the Outputs and enumeration bases report (PDF, 661 KB).

You can find more information about how we define who is a resident or visitor in the People to be counted section of the 'Output and enumeration bases: residential address and population definitions for Census 2021' report.

Following this, we began a comprehensive programme of research and development. We provide a full list of the tests used in the development of these questions in Annex 1. Further details are provided in the summary of testing for Census 2021. References to tests take the form (Year:Test number). For example, the fifth test conducted in 2017 would be referenced as (2017:5).

The tests utilised a range of qualitative and quantitative research methods. A short description of the different research methods and sampling techniques is given in the question and questionnaire development overview for Census 2021. Testing included respondents from a wide range of backgrounds and household types.

In December 2018 the government presented to Parliament a White Paper Help Shape our Future: The 2021 Census of Population and Housing in England and Wales (PDF, 967KB). This outlined our proposal to ensure that online functionality is designed to meet GDS Standards, minimises respondent burden and improves data quality.

The questions for Census 2021 are now finalised. We have evaluated the questions for their potential impact on data quality, public acceptability, respondent burden, financial concerns and questionnaire mode. We present details of this evaluation in Annex 3.

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4. Research that led to the 2019 Rehearsal question design

As part of our preparations for Census 2021, we held a census rehearsal in autumn 2019. The rehearsal provided an important opportunity for us to test the processes, systems, and services we will need to use for Census 2021.

To enable this, the rehearsal questionnaire had to be agreed earlier in the year. As the enumeration section of the form is crucial to ensuring Census 2021 is a success it was agreed that development of these questions would continue in parallel with preparations for the rehearsal.

Therefore, in the White Paper Help Shape our Future: The 2021 Census of Population and Housing in England and Wales (PDF, 967KB), we stated that we were finalising the questions for Census 2021.

Collection of names

Names have been collected in the census since 1841. In earlier censuses respondents entered their full name in one box. For the 2011 Census respondents were asked for the first time to enter their first name and last name in separate boxes.

2011 Census

In 2011, the name of respondents was collected in three locations in the paper questionnaire.

  • in the household listing,

  • in the relationship questions, and

  • at the start of the questions about each person in the household.

Names of visitors were also collected. In all cases first and last name were collected.

On the electronic questionnaire each name was entered once, and then automatically inserted into further questions throughout the questionnaire. For example, into the relationship questions and visitor section.

Middle names

To meet an ONS operational need to improve the matching of census records to the Census Coverage Survey, and other data sources, we investigated collecting middle names. This was also requested during the topic consultation by some genealogists.

We asked respondents' views of the middle name question during cognitive testing of the population base and visitor questions (2018:33). Respondents that lived with family members knew middle names and were happy to provide them. Some respondents in family households entered it into the first name write-in box before being asked. They saw it as important and they were surprised that middle name was not on the form.

Middle names of non-family household members were not well known and were more difficult to provide in households with different cultural naming conventions.

For Census 2021, we will collect middle names of all residents. On the paper questionnaire it is collected at the start of the questions about each individual in the household. In the household listing and the relationship matrix no change has been made due to space constraints and the need to minimise respondent burden.

On the electronic questionnaire, a middle name field has been added to the household listing as this is the only place name is collected.

We will not ask for middle names of visitors.

Paper questionnaire household listing design

Our aim in developing the questions used to count residents and visitors was to collect this data in a way that was consistent with previous censuses. For this reason, on the paper questionnaire these questions have not changed since the 2011 Census.

There are some changes to the structure of the form, household paper questionnaire will collect up to five persons in the household. After that, a continuation questionnaire is needed for larger households. This is discussed in Question and questionnaire development overview for Census 2021.

Additionally, some instructional material on who to count has been moved from the questionnaire itself, into a separate guidance leaflet. You can find the household paper questionnaire in this collection. More information on the guidance leaflet is provided in Annex 2.

Online questionnaire resident listing design

Census 2021 is online-first, so we need to ensure that we count residents and visitors on the electronic questionnaire in the best way possible. Since the last census in 2011 digital technology has changed greatly. We need to ensure our online functionality minimises respondent burden while ensuring data quality is maximised.

Prior to the 2019 Rehearsal our research and testing investigated three approaches for the online questionnaire. These were:

  • Approach 1: 2011 Census design

  • Approach 2: Collect names of residents split across 4 types of resident

  • Approach 3: Collect names of residents split across 3 types of resident

The first approach was tested in the 2017 Census Test. The third approach was used in the 2019 Rehearsal.  Two further approaches were tested following the 2019 Rehearsal, these are discussed in the section Research that led to the recommended Census 2021 question design.

User experience (UX) testing

The questions have undergone significant user experience (UX) testing (2017:2, 2018:2, 2019:1, 2020:2). UX testing focuses on understanding user behaviours as people interact with online services. Through observation techniques, task analysis and other feedback methodologies, it aims to develop a deep knowledge of these interactions and what it means for the design of a service.

UX research on the online questionnaire has taken place on a rolling basis since 2017. Before the Census Rehearsal in October 2019, 458 interviews were conducted at 99 events. The UX testing programme continued in 2020 and has now ended. All participants were purposively selected to include a wide range of ages and digital abilities and understanding of the questions counting residents and visitors was a focus of these interviews.

UX testing included various iterations of the questions described elsewhere in this report. Feedback from this research informed decisions made on the design of these questions.

Approach 1: 2011 Census design

We began our testing programme by conducting usability testing (2016:1 and 2016:3) of the 2011 Census electronic questionnaire on mobile devices. Online completion is expected to be a frequent method of completion in Census 2021.

In this design the questions are presented in the same way as they are on the paper form, leading to a large volume of text on some pages. Additionally, all names were collected on a single page, with the respondent selecting a button to add another for each new name.

The findings showed that the questions aimed at counting household residents were capturing incorrect data. For example, some participants did not include themselves in the count. The response options caused confusion as participants felt that there was too much information to read and some were unhappy about the amount of scrolling. Several participants were not able to complete the questionnaire on their mobile device without interviewer intervention.

These findings were replicated in the 2017 Test  which used a design very similar to the 2011 Census. The names of everyone living in the household were collected on the same page by using the plus symbol button.

This increased the complexity of the task on small screens and caused unnecessary burden, particularly for people with low digital skills. For instance, adding all names on the same page led to long pages for large households. People also put the same person in more than once as they could not recall who they had already added.

When intending to move to the next screen, some people mistakenly pressed the plus symbol button again, they were then unable to close the name and move on.

In addition, people with more complex living arrangements, such as those with lodgers, or whose children lived with another parent part of the time, were not sure who to count.

The same issues were encountered during further user testing of the 2017 Test design (2018:2 and 2019:1).

Based on these findings, and in line with GDS guidelines, we suggested to improve the quality of data collected by:

  • collecting one name per page only

  • replaying the names entered so the household would "build" as the person progresses through the form

  • include the definitions provided as supplementary information on the paper questionnaire's accompanying guidance leaflet

In addition, throughout this testing, there was low public acceptability for asking about visitors. Separately to the work on developing the questions, we conducted work to understand why the visitor questions were not acceptable.

Collect names of residents split across types of resident

Based on feedback from the 2017 Test and user experience testing, two further approaches for counting household residents and visitors were tested ahead of the 2019 Rehearsal. We cognitively tested (2018:33 and 2018:42) both designs in three phases.

Both versions removed the check box question on the types of resident and the question on number of residents as there is no data need for these questions. They also collected names over multiple pages to reduce the amount of information on each screen:

  • Approach 2: A four-stage design with questions like "Do you usually live here?", "Who else lives here?", "Is anyone away?" and "Is anyone staying temporarily?".

  • Approach 3: A three-stage design with questions like "Do you usually live here?", "Who else lives here?" and "Apart from those included is there anyone else who should be added?".

In these designs the intent was that the later stages act as reminders to prompt for household members that may have been forgotten.

In both approaches the initial questions were the same and were well understood. These questions remained largely the same throughout all iterations of testing, though the accompanying guidance was further developed to aid understanding of the concept "usually live"

As personal information should only be collected where needed, the first question asked is "Do you usually live at [the address]?" with the answer options "Yes, I usually live here" and "No, I don't usually live here". This allows those completing the form on behalf of someone else to be routed around the subsequent question "What is your name?".

Identifying that the respondent lived there and collecting their name ensured that the participant had invested in the survey before being asked questions about other household members.

Approach 2: Questions split across four types of resident

Testing (2018:33) found that in most cases the household was captured in the first two stages ("Do you usually live here" and "Who else lives here"), thus participants reported a lot of repetition.

The question on "Who else lives here" was also generally understood, however, there were some participants who had correctly added all household members at the first and second question, who found the third and fourth questions confusing. Some deleted household members after reading them, others added them again and caused overcount.

Based on feedback from this phase of testing this approach was rejected. It was also recommended that:

  • respondents should be able to edit and remove household members more easily (in advance of a summary page at the end of the section).

  • extra guidance should be made available regarding who should be included, and which address should be captured in an accordion.

The third stage, asking about anyone that was missed, was retained as this was needed to help those with more complex households to include all residents.

Approach 3: Questions split across three types of resident

The second and third phase of the cognitive testing (2018:42) focused on the three-stage design.

As in the previous round of cognitive testing (2018:33), participants felt that the questions were repetitive where they had successfully included all household members in the first two stages. This increased burden and caused confusion.

In addition, the stages of the question continued to be misinterpreted as trying to distinguish between permanent and temporary household members. This resulted in frustration and overcount.

The summary of names on each question page helped participants to ensure their responses were correct but did not eliminate the confusion caused by the questions.

Online questionnaire overnight visitor listing design

The purpose of the visitor questions is to ensure that everyone is counted in the census. All visitors should be included, even if they have been included on a census questionnaire at another address. We use the information on visitors solely to produce statistics on the size of the population.

As with the resident listing, initial UX testing (2017:2) removed the questions on type of and number of visitors as these are not needed from a data perspective. However, it was quickly shown that the type of visitor question was needed to separate the resident suite of questions from the visitor questions, so the question was reinstated as a check box question with the same options as on the paper form question H4.

Although this did help to distinguish between residents and visitors, and identify who might be a visitor, participants continued to find the distinction confusing. In addition, the purpose of these questions was questioned, with participants being reluctant to provide information on their guests. To understand the broader level of acceptability when asking residents about any visitors staying at their home on census night, we asked these questions in a small-scale nationally-representative quantitative survey in England and Wales (2018:34).

Two-thirds (66%) of respondents felt it was acceptable to ask about overnight visitors.

Approximately half of respondents who were uncomfortable with the visitor question felt that there was nothing that ONS could do that would make them comfortable answering this question.

However, approximately a fifth of those with concerns would find more information on why the question was asked helpful. Others were worried about including visitors, as they felt this would be creating "overcount" as they would also be included at their home address if this were in the UK.

We addressed these issues in the design for the online questionnaire by the inclusion of a guidance accordion which explained why this information was needed, what the data would be used for, and that double counting of people was not a risk.

This is not achievable on the paper questionnaire because of space constraints.

Finalising the 2019 Rehearsal design

The 2019 rehearsal design was a refinement of Approach 3. The overall user journey for the collection of names of residents in the 2019 Rehearsal was:

  • Question 1: Do you usually live at [address]?

  • Question 2: [If "Yes" at Q1] What is your name?

  • Question 3: Does anyone else live at [address]?

  • Question 4: [If "Yes" at Q3] Who do you need to add to [address]? [Returns to Q3]

  • Question 5: [If "No" at Q3] Apart from the people already included, is there anyone else who is temporarily away or staying that you need to add to [address]?

  • Question 6: [If "Yes" at Q5] Who do you need to add to [address]? [Returns to Q5]

Once the respondent selected "No" at Question 5 they moved onto the questions on visitors. Throughout these questions, as requested by respondents in testing, all the household members already added are listed at the top of each page. This means the respondent can see who they have added. Next to each listed name are options to change the name or to remove the name. This allows spelling errors, or mistakenly added entries to be corrected immediately.

The overall user journey for collection of visitor information in the 2019 Rehearsal was:

  • Question 7: Are there any visitors staying overnight on 13 October 2019 at [address]?

  • Question 8: [If not "No" at Q7) What is the name of the visitor staying overnight on 13 October 2019 at [address]?

  • Question 9: Are there any other visitors staying overnight on 13 October 2019 at [address]? [If "Yes" at Q9 returns to Q8]

As with residents, the names already input are listed at the top of each page with options to change or remove. Once the respondent selects "No" at Question 9 they moved onto a summary page:

  • stating how many household members they have added

  • listing the names of the household members

  • stating how many visitors they have added

  • listing the names of the visitors

This approach overcame some of the key issues with the 2011 Census design:

  • collection one name per page allowed the respondent to have a sense of progressing and works well on a mobile device.

  • constantly replaying the names input in a list at the top of each page, with options to change or remove each entry, allows respondents to see who is already input and to immediately notice and correct any mistakes.

However, other key issues remained. Many participants found the third stage questions on residents confusing, and those with more complex living arrangements remained unsure who to count.

Therefore, it was agreed to continue development of these questions after the 2019 Rehearsal design was finalised. This allowed an additional year of development to take place before making a recommendation for Census 2021.

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7. Annex 1: Summary of research undertaken for the questions that count residents and visitors, 2017 to 2020

References to tests take the form (Year: Test number). "Year" refers to the calendar year the test was undertaken in and the test number is the position of the test within the year considering all testing that took place in that year. For example, the fifth test conducted in 2017 would be referenced as (2017:5).

A full description of each of these items can be found in summary of testing for Census 2021.

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8. Annex 2: Paper first initial contact information leaflet

The information leaflet includes important information the respondent may need to complete the census. The sections of the leaflet are:

  • What the census is and why you should take part

  • Who to include in your census questionnaire

  • Which questions to answer

  • How we use your information and protect your privacy

  • How to get help

The section "Who to include in your census questionnaire" was included as part of the paper form in 2011. The text in the leaflet is as follows.

Who to include in your census questionnaire

People who usually live here

Include everyone who usually lives here. This might include family members, housemates, tenants, or lodgers. This is the address where they spend most of their time and might be their permanent or family home.

People who are temporarily away

Include everyone who usually lives here, but who is temporarily away on Sunday 21 March 2021. This includes:

  • people staying (or expecting to stay) somewhere else for less than 6 months, such as a hospital, care home or hostel

  • members of the Armed Forces

  • people staying at another address for work, holiday, travel or staying with friends or relatives (unless they are outside the UK for a year or more)

  • people in prison with a sentence of less than a year, or on remand

People temporarily staying here overnight on Sunday 21 March 2021

Anyone who does not have another UK address should be included on your census form as a member of your household. This includes:

  • people from the UK who do not have another address

  • people from outside the UK who plan to stay in the UK for three months or more

Anyone who usually lives at another address should be included on your census form as a visitor. This includes:

  • people who usually live at another UK address, such as boyfriends, girlfriends, friends, or relatives

  • people who are staying here for work, whose permanent or family home is elsewhere

  • people who usually live outside the UK and are staying in the UK for less than three months

  • people here on holiday

People who stay at more than one address

People with more than one UK address should be included on the census form at their permanent or family home. If they do not have a permanent or family home, they should be included on the census form at the address where they spend most of their time.

Children with parents who live apart

Children should be included on the census form at the address where they spend most of their time. If they spend time equally between two addresses, include them on the census form at the address where they are staying overnight on Sunday 21 March 2021.

Boarding school children and students away from home during term time

Include boarders and students staying away from home in the questions about who lives in this household. They will also be included on the census form at their term time address.

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9. Annex 3: 2019 Rehearsal question evaluation

Evaluation of name, type, and number of residents and visitors' questions used in 2019 Rehearsal

Potential for impact of these questions on public acceptability and financial concerns were assessed as "Low".

Potential for impact on data quality: "Over threshold -- further development needed"

The definitions of residence are very complex. The online question suite used in the 2019 Rehearsal was not sufficiently developed for use in Census 2021. Respondents were not clear on who to include when providing the number and type of residents in household.

Additionally, those in shared accommodation may not know the full names of all those they live with.

Qualitative testing of the Census 2021 final design suggests that this suite of questions will have a medium potential for impact in 2021. Issues with the respondent not knowing all members of the household cannot be addressed through questionnaire design.

Potential for impact on respondent burden: "Over threshold -- further development needed"

In the 2019 Rehearsal (2019:15) respondents took 20 seconds on each resident and visitors' question, longer than the average (15 seconds) for similar type of questions.

In addition, 2.11% of participants used the previous button during the visitors' question suite, over the threshold (2%) of concern.

Qualitative testing of the Census 2021 final design (2019:17) suggests that this suite of questions will have a medium to low potential for impact in 2021. Although the questions still take time to navigate, they are clearly understood and considered logical by respondents.

Potential for impact on questionnaire mode: "High"

As described in this report, the online question suite for 2019 Rehearsal was completely different to the paper questionnaire collection of name, type, and number of residents, because of using a multi-page sequential approach. The difference in collection was made to meet GDS standards and provided minimal guidance information. On paper substantial definitional information is contained either in the questionnaire, or the accompanying guidance booklet (shown in Annex 2).

Inclusion of the definitional information in the Census 2021 final design suggests that although the paper and online designs remain very different this suite of questions will have a medium to low potential for impact in 2021 as they will both collect the count and names of household residents and visitors effectively.

Evaluation of visitor's details questions

These questions have not substantially changed between 2019 Rehearsal and the Census 2021 final design. Therefore, the 2019 Rehearsal question evaluation is expected to apply to the Census 2021 questions.

Potential for impact of these questions on public acceptability, financial concerns and questionnaire mode was assessed as "Low".

Potential for impact on data quality: "High"

These questions have a chance for recall bias and captures information that cannot be observed. Respondents may not know the date of birth or full address of their overnight visitors.

In addition, the visitor sex question had a non-response rate that was above the quantitative acceptance threshold questions (7%). The dropout rate was above the acceptance threshold of 1%. 4.7% of total page views used the previous button, above the 2% threshold.

Potential for impact on public acceptability: "Medium"

This question had negative feedback from the 2019 Rehearsal on issues relating to public acceptability. Testing (2018:34) found only 66% of respondents thought it was acceptable to ask about overnight visitors in general. We have added guidance accordions to help address this.

Potential for impact on respondent burden: "High"

Analysis of the 2019 Rehearsal found that for each of these questions:

  • item non-response rate was above 7% threshold  

  • the dropout rate was above the 1% threshold

  • use of the previous button was above the 2% threshold

In addition, the questions include write-in fields, increasing the burden for respondents to answer the question. However, in Census 2021 on the electronic questionnaire respondents will be able to use standard postcode look-up functionality on the visitors address question.

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