Our new blog questions the assumption that a self-identified sex question in the 2021 census will not affect data reliability. Drawing on data from a Swedish study, we argue that the potential effect on subgroups should be addressed as a matter of urgency. murrayblackburnmackenzie.org/2020/06/04/a-n…
Proposed guidance for the sex question in the 2021 census frames it as a question about self-declared gender identity. Here is the guidance proposed by the Office for National Statistics for the census in England and Wales: 
This is the guidance proposed by the National Records of Scotland:
This is the guidance proposed by the Northern Ireland Statistics and Research Agency:
Social scientists who work with population level data have consistently raised concerns about the potential impact of framing the sex question in this way on the integrity of the data collected and quality of analysis possible using this data.
In September 2019 a group of social scientists with expertise in quantitative analysis wrote to the Scottish Parliament Culture, Tourism, Europe and External Affairs (CTEEA) Committee about their concerns: parliament.scot/S5_European/Ge…
In December 2019, 80 of the UK’s most eminent social scientists wrote to the three census authorities, setting out their concerns, in particular about the potential impact on data reliability at the subgroup level. thetimes.co.uk/article/census…
Such concerns are supported by a Swedish study which found that amongst young people aged 22 to 29 years, 4% identified as members of the opposite sex, and that 6.3% wanted to be treated as members of the opposite sex.
As we wrote earlier this year, in Belgium, levels of applications to change legal sex from female to male amongst those aged 16-24 years old were around five times higher than would be expected from the population share of women that age. mbmpolicy.files.wordpress.com/2020/02/gender…
It's not difficult to see how data integrity might be damaged at the subgroup level by the proposed framing of the sex question as a self-declared gender identity question. Such effects are likely to be further exacerbated when sex & age are cross-referenced with other variables.
Despite increasing concerns about data reliability, as far as we've been able to establish, no organisation which supports inclusion of self-identification guidance has demonstrated that they've considered the potential impact on data reliability at the population subgroup level.
On 30 January 2020, when giving evidence to a committee of the Scottish Parliament, representatives of NRS failed to respond to a question from Convener Joan McAlpine MSP about the impact on subgroup population data. parliament.scot/parliamentaryb…
At an evidence session in September 2019, NRS’ then director of statistical services Amy Wilson acknowledged that despite similar guidance being introduced in the 2011 census (albeit without any democratic oversight or wider scrutiny) the effect on data quality remained unclear.
Professor Sullivan and her co-signatories did not receive a response to their letter from the census authorities until 26 February 2020, nor did the response address their substantive concerns.
While the census authorities indicated that they would provide an opportunity for the signatories to engage in further discussions, it is our understanding that almost six months after they raised their concerns no such meeting has yet taken place.
Professor Sullivan has also written about her experiences of raising concerns with the census authorities, and how this led to her being no-platformed by social research organisation NatCen. tandfonline.com/doi/full/10.10…
In April 2020 we submitted Freedom of Information requests to ONS, NRS and NISRA, asking what analysis they had undertaken to estimate the impact on subpopulation data reliability. The responses received from ONS and NRS indicate that neither has undertaken any such analysis.
Research commissioned by NRS and undertaken by ScotCen in 2019 revealed that 3% of the general population sample would not complete the census if guided to answer based on either their legal (as opposed to biological) sex or self-declared gender identity. scotlandscensus.gov.uk/documents/Scot…
Census data matters. It matters because it drives public spending priorities and decisions about resource allocation. Introducing the recent House of Lords debate on the Census (England and Wales) Order 2020, Cabinet Office Minister Lord True stated:
Census data also acts as the denominator for calculating disease prevalence rates. There is, for instance, a pressing need for robust, high quality data which is disaggregated by sex, age, ethnicity and other key demographic variables on outcomes related to Covid-19.
The UK Code of Practice for Statistics states: statisticsauthority.gov.uk/wp-content/upl…
We believe that the material above strongly suggests a failure by the census authorities to properly engage with and investigate the data reliability concerns raised by relevant data experts and that this represents a departure from the requirements of the Code.
We also question the assumption that clearly defined data on sex is no longer required or relevant for the purposes of the UK’s most important data collection exercise, despite strong statements about the importance of sex made by the census authorities themselves.
