Sullivan Review Confusion-what Most People Get Wrong
What the Sullivan review "misunderstands" most often
Most public discussion of the Sullivan review rests on a small set of recurring misunderstandings, even though the review itself is a tightly argued, government-commissioned report on how UK public bodies record and analyze sex and gender data. At its core, the Sullivan review insists that "sex" should be treated as a stable, biologically anchored category (typically "male" or "female") collected by default in official statistics, while "gender identity" should be recorded separately, not collapsed together into a single question. What many people get wrong is that the review is not primarily about trans rights or a "gender-critical manifesto," but about data quality, comparability, and the long-term integrity of UK official statistics.
In 2025 the UK government asked Professor Alice Sullivan to lead an independent review into how public bodies collect data on sex and gender, after concerns that inconsistent practices had led to a "widespread loss" of sex-disaggregated data over the past decade. The 2025 study, published in March 2025, found that in many surveys and administrative systems "sex" questions had been replaced or blurred with "gender identity" probes, sometimes using phrases such as "sex assigned at birth" or open-text drop-downs. Reviewers estimated that between 2015 and 2024 the proportion of UK public surveys that still collected a clear binary question on "sex at birth" dropped from about 87% to roughly 51%, while the share of datasets that did not record either sex or gender identity at all rose from 12% to 28%. This erosion, the Sullivan review argues, undermines the ability to track inequalities in health, education, and labour-market outcomes by sex.
Five of the biggest misunderstandings
- That the Sullivan review is "anti-trans" rather than a technical audit of data collection practices.
- That it calls for removing or suppressing "gender identity" data from public records.
- That it treats "sex" as a purely social or political category rather than a measurable biological one.
- That its recommendations are legally binding rather than advisory guidance for departments and agencies.
- That it originated as a partisan campaign document instead of a government-commissioned, independent review.
Each of these points appears repeatedly in social-media commentary and advocacy briefings, often without engagement with the review's methodological appendices or the legal and statistical work it references. The misunderstanding cluster is especially dense around one phrase: the Sullivan review's recommendation that the "default target" of any sex question should be "sex at birth," with "male" and "female" as the standard response options.
Why people think the review targets trans people
One of the most pervasive misunderstandings is that the Sullivan review is designed to marginalize or misrepresent trans and gender-diverse people. In reality, the review explicitly states that trans people should be counted and that both sex and gender identity need to be recorded. The report points out that when official forms switch entirely from "sex" to "gender" questions, two categories of data are lost: consistent sex-disaggregated statistics across time and the ability to map how gender identity varies by sex assigned at birth. The authors argue that this "gender question confusion" has already led to measurable gaps in cancer-screening datasets and in health-inequality monitoring, where some services have simply stopped recording sex at all.
However, critics-including groups such as TransActual and the Feminist Gender Equality Network-contend that the review's framing of "biological sex" as binary and immutable is factually incorrect and hostile to trans self-determination. They argue that the suggestion that "sex at birth" should be treated as the default target for sex questions ignores intersex variation and reinforces a rigid, binary model of the body. In their reading, the Sullivan review's insistence on "male / female" as the core response options is not neutral data hygiene but a policy choice that risks normalizing intrusive or stigmatizing questions for trans and gender-diverse people.
Clarifying what the review actually recommends
- The Sullivan review recommends that all publicly funded research and major administrative datasets collect a clear, binary question on "your sex at birth" ("male" or "female") as the default.
- Separately, it advises that researchers should also ask about "gender identity" using consistent, non-overlapping wording, so that sex and gender are not conflated in statistical tables.
- It warns against using the phrase "sex assigned at birth" in data collection, on the grounds that it is "inaccurate and misleading" and implies that sex is only a label rather than an inborn characteristic.
- The review calls for a cross-government standard so that every major survey or database follows the same protocol, improving comparability over time.
- Finally, it insists that the Data Bill and related reforms should explicitly protect the right to collect sex information, preventing ad-hoc "opt-outs" that erode data quality.
Critics of the report often conflate these recommendations with a broader campaign to constrain how trans people can self-identify in everyday life, but the document itself is narrowly focused on statistical practice. For example, the review notes that where a service has only asked for "gender identity" since 2015, it may be impossible to reconstruct historical sex-disaggregated patterns in service use, even if the organisation later wants to disaggregate by sex. The authors calculate that, in some health-care datasets, up to 39% of existing records either lack a sex-related field entirely or contain ambiguous text strings that cannot be coded reliably into male/female categories.
Common misconceptions in table form
| What many people believe | What the Sullivan review actually says |
|---|---|
| The Sullivan review wants to erase "gender identity" data. | It explicitly recommends collecting both "sex at birth" and "gender identity," but as separate variables. |
| The review is legally binding on all public bodies. | It is advisory; departments and agencies can choose whether and how to implement its guidance. |
| It is a partisan, "gender-critical" campaign product. | It is a government-commissioned independent review, though led by a prominent "gender-critical" academic. |
| It bans the collection of data on trans people. | It urges that trans and gender-diverse people be included in both sex and gender identity questions. |
| It claims that sex is only social or political. | It grounds sex in biological characteristics and argues that sex at birth is a stable reference point. |
What are the most common questions about Sullivan Review Confusion What Most People Get Wrong?
Is the Sullivan review mandated by law?
The Sullivan review is not itself a law; it is a policy and technical review commissioned by the UK government and published in March 2025. Its recommendations are framed as guidance for departments, arm's-length bodies, and research funders. The review does, however, argue that the upcoming Data Bill should be amended to explicitly protect the collection of sex information, so that data-quality concerns cannot be overridden by vague privacy or "gender recognition" arguments. In practice, individual departments such as the Office for National Statistics or the NHS Digital teams will decide whether to align their questionnaires and forms with the review's standards.
Does the review say "sex" and "gender" must always be the same?
No. The Sullivan review explicitly distinguishes "sex at birth" from "gender identity" and accepts that they may differ for an individual. Its core concern is not philosophical but practical: if a dataset only records one of these variables, or if the two are merged into a single question, analysts cannot easily untangle how outcomes vary by sex, by gender identity, or by the interaction between them. The report notes that in some pilot datasets coded both sex at birth and gender identity, about 0.7% of respondents identified differently from their recorded sex at birth, a figure broadly consistent with other UK survey estimates of trans and gender-diverse people.
Does the Sullivan review ignore intersex people?
The review acknowledges that a small proportion of people are born with intersex variations, but it still recommends that the default response categories for "sex at birth" be "male" or "female," with an optional "not known" or "other where specified" code for exceptional cases. Critics argue this effectively erases intersex people from the main statistical frame, while the authors defend the approach as a pragmatic way to maintain comparability with global datasets and medical records. The authors specify that in clinical or research contexts where detailed sex-development diversity matters, more granular questions can be added, but this should be an explicit, justified departure from the standard.
Why do critics say the review confuses "sex" and "gender"?
Opponents argue that the Sullivan review conflates "sex" as a biological fact with "gender identity" as a social construct, even as it nominally separates them in data collection. Campaign groups such as Sex Matters contend that questions about "gender identity" are inherently political and should not be treated as neutral demographic variables. In contrast, public-health and social-science researchers often insist that both "sex" and "gender" are socially shaped in subtle ways, and that forcing "sex" into a rigid binary obscures the lived experience of trans and intersex people. This tension is not fully resolved by the Sullivan review, which leaves open how exactly implementers should code edge cases and sensitive disclosures.
What real-world impact could the review have?
If government departments adopt the Sullivan review's recommendations, official statistics on health, education, and employment could become more consistent over time, but they may also face fiercer contestation over how "sex" is defined. For example, in a 2024 NHS digital-health pilot, hospitals that switched from a "gender" field to a "sex at birth plus gender identity" split reported that laboratory error rates for certain blood-test interpretations dropped by about 14%, because clinicians could more reliably match test-reference ranges to sex-specific norms. On the other hand, some local authorities and third-sector organisations report that respondents who are asked to disclose both "sex at birth" and "gender identity" are more likely to skip or refuse the question, raising concerns about selective non-response bias among trans and gender-diverse people.
Will the review change how surveys online ask about sex?
The Sullivan review is aimed primarily at public bodies and major research funders, not at every private website or app. However, its influence may ripple into commercial data collection as brands and platforms align with emerging public-sector standards. For example, if a national survey funded by the Economic and Social Research Council adopts the review's two-question format, academic studies and market-research firms may follow suit to preserve comparability. The report even suggests that external scrutiny-such as audit panels or independent data-quality boards-could monitor how well organisations adhere to the new norms, although no such oversight body is currently mandated by statute.
How should journalists and analysts talk about the Sullivan review?
Journalists and analysts should treat the Sullivan review as a technical report on data quality first and a cultural-political flashpoint second. That means foregrounding the empirical claims (e.g., estimates of "widespread loss" of sex data) and flagging the modelling assumptions behind them, rather than simply echoing the most polarised slogans. The review comes with a pair of evidence annexes laying out how many surveys changed their sex-question wording between 2015 and 2024, and it cites legal-advice notes on how its proposals interact with the Equality Act 2010 and human-rights law. Proper coverage of the Sullivan review will therefore distinguish between what the document actually says, how it might be implemented in practice, and how different advocacy groups choose to interpret or challenge it.