1. Overview

The Office for National Statistics (ONS) has conducted a comprehensive programme of research and testing to finalise Census 2021 questions and guidance. The report Census 2021: Final guidance for the question "What is your sex?” is available on our website.

This methodology article provides further detail about the qualitative test, referenced as 2020:61, conducted as part of the review of evidence that fed into the decision-making for both the target concept and the guidance wording. As such, it was conducted at the same time as finalising the concept of sex for the 2021 Census and a range of target concepts were included.

Notes for: Overview
  1. 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 all testing that took place in that year. For example, the fifth test conducted in 2017 would be referenced as (2017:5). A full list of tests is provided in the summary of testing for Census 2021.
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2. Research aims

The aim of the interviews was to understand how different groups responded to different wording and target concepts of the sex question guidance, and the impact it may have on willingness to complete the Census 2021 as a whole and the sex question in particular.

In relation to the target concept, the interviews explored the acceptability of the different options. This included exploration of the potential for a negative impact on overall census response or item level response to the sex question. Within this we explored the potential for this to disproportionately affect specific subgroups of the population, for example, women or trans people1.

In relation to the guidance wording, the interviews explored the acceptability and clarity of terms used within the draft guidance.

Notes for: Research aims
  1. The trans population is defined as the population whose gender identity differs from their sex registered at birth. This includes those with non-binary identities.
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3. Sample

Earlier research on the sex and gender identity questions is detailed in Sex and gender identity question development for Census 2021 and included research into the guidance for use in the 2019 Rehearsal. This had previously identified that the sex question, and the associated guidance, could negatively affect response rates among the trans population.

Following the 2019 Rehearsal, we identified that there was also a risk to response rates in other populations. The sampling criteria therefore considered:

  • trans status: trans and cisgendered people
  • organisation membership: representatives from trans ally groups and women’s groups
  • age group: people aged 16 to 29 years old, 30 to 59 years old, and 60 or more years old

In total, 52 participants were recruited from the general population representing a mix of these criteria. 16 participants were trans, 7 participants were members of trans ally groups and 16 participants were members of women’s groups. 16 cisgender participants were not members of either a women’s group or a trans ally group and included males and females. These groups are not mutually exclusive so one participant may be in more than one of these groups. A range of geographical locations were represented in the testing.

Participants were recruited through existing databases containing individuals who had “opted-in” to take part in future research and via a professional agency. Screening questions were used to determine eligibility and the research topic was not known to participants prior to the interview. Membership of any women’s or trans ally group was sufficient to meet the sampling criteria.

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4. Research method

One-to-one interviews were conducted remotely via video conferencing software and in line with the Code of Practice for Statistics and best practice for Government Social Research.

Interviews explored participants’ interpretations of the sex and gender identity questions before cognitively testing four versions of the guidance, with varying target concepts, and guidance wording. This wording had been further developed from the version used in the 2019 Rehearsal, to take into account feedback received during and after that event. For example:

  • information on “Why we ask this question” has been moved to the top of the page as research found this was important to encourage response (2020:5); this has been applied to guidance for all questions

  • all references to specific population groups have been removed; this ensures that the guidance remains relevant to all potential readers and removes terms that are not universally acceptable to the communities being described

The versions of the guidance were shown to participants in different orders in a between-participants design to reduce order effects.

The interviews also included an in-depth discussion of methods participants have used in the past to provide feedback to businesses or public organisations, such as the Office for National Statistics (ONS), on their goods or services. This was then used to gauge strength of feeling and likelihood of action when discussing the actions they could take when presented with each of the guidance options being tested.

Full analysis of the interview content was conducted independently by two researchers before comparing and agreeing findings. This was then quality-assured by a third team member. The analysis considered the potential for the order the guidance was presented in to have affected findings.

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7. Outcome

These results formed part of the detailed evaluation of the target concept of sex for Census 2021 reported in the Methodology for decision making on the 2021 Census sex question concept and associated guidance.

They also formed part of the evaluation of the final guidance wording. The final wording is reported in Census 2021: Final guidance for the question "What is your sex?”.

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