Summary

Sex, gender identity, and sexual orientation are complex constructs that are interrelated but conceptually distinct. These concepts are also key indicators of the demographic diversity in the United States. Sex and gender are often conflated under the assumptions that they are mutually determined and do not differ from each other; however, the growing visibility of transgender and intersex populations, as well as efforts to improve the measurement of sex and gender across many scientific fields, has brought to light the limitations of these assumptions and demonstrated the need to reconsider how sex, gender, and the relationship between them are conceptualized. This in turn affects the concept of sexual orientation, because it is defined on the basis of the relationship between a person’s own sex or gender and that of their actual or preferred partners. Sex, gender, and sexual orientation are core aspects of identity that shape opportunities, experiences with discrimination, and outcomes through the life course; therefore, it is crucial that measures of these concepts accurately capture their complexity.

Better measurement of sex, gender identity, and sexual orientation will also improve the ability to identify sexual and gender minority populations and understand the challenges they face. The social, political, and legal status of lesbian, gay, bisexual, transgender, queer, intersex, and other sexual and gender minorities—the LGBTQI+ population—has undergone considerable change in the past decade. Although there has been growing public acceptance, LGBTQI+ people continue to experience disparate and inequitable treatment, including harassment, discrimination, and violence,

which in turn affects outcomes in many areas of everyday life, including health and access to health care services, economic and educational attainment, and family and social support. Though knowledge of these disparities has increased significantly over the past decade, glaring gaps remain, often driven by a lack of reliable data.

A 2020 report from the National Academies of Sciences, Engineering, and Medicine (the National Academies) called on the federal government to develop standards to guide the collection of these data throughout the activities of the federal agencies. Without national standards on how to collect, analyze, and report these data, there are increasing differences in the measures that are used in surveys and other data collections. Some of these differences reflect important attention to the data collection context or to variation in terminology across the population, but other differences reflect a lack of consensus on how to define and measure the constructs of interest. A lack of consistency in data collection measures introduces concerns about data comparability, complicates data analysis and reporting, and hinders efforts to advance research and develop effective programs and policies focused on improving the well-being of LGBTQI+ people.

To improve the quality of data collection efforts and advance research and policy around LGBTQI+ population well-being, the National Institutes of Health asked the National Academies to convene a committee of experts (1) to review current measures and the methodological issues related to measuring sex as a nonbinary construct, gender identity, and sexual orientation in surveys and research studies, in administrative settings (such as grant and job applications), and in clinical settings (such as doctors’ offices or clinical trials), and (2) to produce a consensus report with conclusions and recommendations on guiding principles for collecting data on sex, gender identity, and sexual orientation and recommended measures for these constructs in different settings.

Due to the broadness of the settings and the short timeline of study, the committee focused on data collection efforts among adults in the general population; therefore, modifications may be necessary when data is being collected for youth or within LGBTQI+ communities.

To carry out its task, the panel first agreed on the definitions and characteristics of the underlying concepts on which our recommended measures would be based; we also identified and defined terminology that we use to describe specific sexual and gender minority populations: see Table S-1. It is important to note that these populations represent only a subset of sexual and gender minority populations in the United States.

In accordance with federal mandates for data collection on American Indian and Alaska Native (AIAN) populations and in response to

recommendations of the National Congress of American Indians and the Indian Health Service 2020 Strategic Vision and Action Plan, the panel affirms the importance of ensuring the representation and visibility of the U.S. Indigenous population. “Two-Spirit” is an intertribal umbrella term that serves as an English-language placeholder for tribally specific gender and sexual orientation identities that are centered in tribal worldviews, practices, and knowledges. Tribes have their own specific term for gender statuses (e.g., in Navajo, Nádleehí refers to one who is transformed), and many go beyond the binary construct of male or female and are part of a holistic view of personhood that encompasses not only gender or sexual orientation identity, but also a social and cultural position that shapes and defines all aspects of one’s life. Tribal identities cannot be directly translated or mapped to the standard Western conceptions of gender and sexuality. Two-Spirit is a way to reference Indigenous identities, practices, and traditions in the context of Western data collection practices and ensure that Indigenous sexual and gender minorities are represented and counted. Because Two-Spirit is a term by and for Indigenous peoples and is culturally anchored with particular meaning and, potentially, social status, it is not appropriate for use by non-Indigenous populations.

TABLE S-1 Definitions and Terminology for “Sex,” “Gender,” and “Sexual Orientation”

NOTE: Populations and identities listed are a subset of all sexual and gender minority populations.

^a DSD, differences in sex development.

PRINCIPLES FOR DATA COLLECTION

The panel developed five guiding principles for data collection.

1. People deserve to count and be counted (inclusiveness). A key purpose of data collection is to gather information that can help researchers, policy makers, service providers, and other stakeholders understand diverse populations and create policies, programs, and budgets that meet these populations’ needs. Both quantitative and qualitative data, regardless of how they are collected, reflect the identities and experiences of people and communities that deserve to be heard and respected. Everyone should be able to see themselves, and their identities, represented in surveys and other data collection instruments.
2. Use precise terminology that reflects the constructs of interest (precision). Sex, gender, and sexual orientation are complex and multidimensional, and identifying the components of these constructs that are of interest and measuring them using appropriate terminology is critical for collecting reliable data. Questions should clearly specify which component(s) of sex, gender, and sexual orientation are being measured, and one construct should not be used as a proxy for another.
3. Respect identity and autonomy (autonomy). Questions about dimensions of identity, by definition, are asking about a person’s sense of self. Data collection must allow respondents to self-identify whenever possible, and any proxy reporting should reflect what is known about how a person self-identifies. All data collection activities require well-informed consent from potential respondents, with no penalty for those who opt out of sharing personal information about themselves or other household members. This principle encompasses data collection for legal documents intended for individual identification; external authorization or attestation should not be required when someone reports, or wishes to change, their gender identity.
4. Collect only necessary data (parsimony). Data collection is not an end in itself: data should only be gathered in pursuit of a specific and well-defined goal, such as documenting or understanding disparities and inequities between populations or meeting legal reporting requirements, and data that are not essential to achieve that goal should not be collected.
5. Use data in a manner that benefits respondents and respects their privacy and confidentiality (privacy). Once data are gathered, they should be analyzed at the most granular level possible, and research

1. findings should be shared back with respondents and their communities to ensure that they benefit from data they have shared. Throughout all analysis and dissemination steps, sex, gender, and sexual orientation data—which may be sensitive and vulnerable to misuse—must be used, maintained, and shared only under rigorous privacy and confidentiality standards. Similarly, when data are collected in tribal nations, preapproved tribal research and data collection, analytic, and dissemination protocols should be followed to ensure data integrity and community benefit and to ensure rigorous privacy and confidentiality standards are upheld.

GUIDELINES FOR COLLECTING SEX AND GENDER DATA

The growing visibility of transgender and intersex populations, as well as efforts to improve the measurement of sex and gender in many scientific fields, has led to a recognition that sex and gender are more complex than current measures capture. For sex and gender, most data collection instruments do not separately assess both constructs and instead conflate them by using a single measure. This single measure sometimes specifies that respondents should report their sex, sometimes that they should report their gender, and sometimes does not specify the concept of interest. However, for transgender and intersex people, sex and gender and their dimensions may not fall in the same category, and data collection efforts that are not clear regarding which specific dimension of sex or gender is being measured make it difficult to determine how they should answer.

This imprecision can lead to mismeasurement of the relevant concept (e.g., when gender identity is reported as sex) or misuse of the data (e.g., assuming none of an individual’s sex traits differ from their reported sex), and this can have negative repercussions for these individuals, as well as for overall data quality. There is growing recognition of the potential harms that can arise from mismeasurement or misuse of measures of sex and gender, particularly in health care, where tests and treatments are sometimes tied to sex-related differences and where gender identity informs social interactions between health care professionals and patients in ways that can affect the quality of care. In general, when a person’s identity documents are not consistent with their reported sex or gender, they can face harassment, discrimination, and restrictions on their activities—such as travel or voting—affecting their ability to live freely in society. Measuring sex as a biological variable based on sex traits is insufficient because it cannot address either the multidimensional nature of sex or the independent role of gender in shaping people’s health and life experiences.

CONCLUSION 1: Gender encompasses identity, expression, and social position. A person’s gender is associated with but cannot be reduced to either sex assigned at birth or specific sex traits. Therefore, data collection efforts should not conflate sex as a biological variable with gender or otherwise treat the respective concepts as interchangeable. In addition, in many contexts, including human subjects research and medical care, collection of data on gender is more relevant than collection of data on sex as a biological variable, particularly for the purposes of assessing inclusion and monitoring discrimination and other forms of disparate treatment.

Although the distinction between gender as a social construction and sex as a biological variable can seem clear on its face, in practice, aspects of gender shape most experiences in everyday life, from internalized psychological processes to structural constraints, such as sexism and other forms of gender discrimination. It is difficult to disentangle the independent effects of sex and gender on other outcomes because of their combined biological and environmental or contextual influences. Gender-based social structures and expectations can influence behaviors and both create or magnify differences that might otherwise appear to be based in biology due to correlations with sex as a biological variable; however, these processes can only be understood if measures of gender are also routinely collected.

RECOMMENDATION 1: The standard for the National Institutes of Health should be to collect data on gender and report it by default. Collection of data on sex as a biological variable should be limited to circumstances where information about sex traits is relevant, as in the provision of clinical preventive screenings or for research investigating specific genetic, anatomical, or physiological processes and their connections to patterns of health and disease. In human populations, collection of data on sex as a biological variable should be accompanied by collection of data on gender.

Asking respondents to separately identify their sex and their gender—in particular, their sex assigned at birth and gender identity—improves overall measurement quality and also allows researchers and other data users to identify individuals with transgender experience by comparing their sex assigned at birth to their current gender identity. This two-step gender measure has become an increasingly common and validated way to identify people with transgender experience because it identifies a wider range of transgender people than single-step methods that ask respondents whether they identify as transgender.

The use of a single binary male/female item to measure sex does not capture either the multidimensional nature of this construct or its underlying complexity for those with intersex traits or transgender people, because their sex traits may not correspond to those of a single sex. Introducing a third response category to binary measures of sex, such as “transgender” or “intersex,” is thus a poor measure of these populations. Moreover, because gender is socially mediated, binary measures of any dimension of gender are also inadequate for capturing the complex ways in which individuals can identify with, express, or socially experience gender.

MEASUREMENT CONTEXT

The panel was tasked with making recommendations on measures of sex, sexual orientation, and gender identity with attention to how these recommendations may be applied differently in three settings: in surveys and research studies, in administrative settings, and in clinical settings. We found that the most relevant characteristics distinguishing these settings were uses of the data, the identifiability of respondents, and the risk of data disclosure. LGBTQI+ people are often subject to mistreatment, segregation, harassment, discrimination, and violence, and therefore reporting information that identifies an individual as a sexual or gender minority may pose risks to respondents. Consequently, respondents should always be able to opt out of providing this information, particularly in contexts where their responses can be linked to personally identifiable information and where the risk of disclosure is high. Even when individuals are not at risk of being identified, when data are broadly available—even in aggregated form—there is the potential for these data to be misused or misinterpreted to support harmful treatment or policies. Thus, it is important to weigh the need for and benefits of collecting these data with the risk of harm such data collection might pose to respondents.

For surveys and research, data are often collected confidentially and reported in aggregate to prevent disclosure of identifiable information about respondents. When those protections are in place, the risk of disclosure is low for individual respondents, enabling the routine collection of data that identifies LGBTQI+ populations. In clinical settings, data are linked to a specific individual, but the information on sex traits, gender identity, sexual orientation, transgender experience, and intersex traits is also crucial for providing appropriate and necessary care. While health-related data are legally protected from unauthorized disclosure, clear organizational policies, work flows, and training on its use are necessary for appropriate care and to prevent mistreatment of LGBTQI+ people.

Data collected in administrative settings are often linked to specific individuals, such as for vital statistics and other legal identification documents to establish identity. However, these data have sometimes been used to facilitate segregation, harassment, and discrimination. In many administrative settings, strong legal privacy protections like those in health care do not exist, so there may be specific contexts in which the collection of some of these data, such as intersex status or sex assigned at birth, may be considered invasive. For these reasons, it is especially important to establish a clear need to collect these data, minimize the risk of data disclosure and misuse, and allow individuals to opt out of responding.

Much of the research that has been conducted on measures of sex, gender identity, and sexual orientation has been conducted with survey data and in research settings. Although less information evaluating the use of these measures in clinical and public health settings was available, the panel saw little reason to believe that our recommended measures need to be modified for these settings. Very little information is available on measurement practices in administrative settings, and it may be necessary to modify the recommended measures in specific administrative contexts. We note that sex assigned at birth, gender identity, and sexual orientation are not the only types of potentially sensitive information that need to be collected respectfully and confidentially and used appropriately in administrative settings. For these reasons, while we propose one set of measures that can be used across all three settings, users should identify and adopt best practices for implementation when using these measures in settings that present risks of identifiability and disclosure.

RECOMMENDED MEASURES

Sexual Orientation Identity

The measurement of sexual orientation has varied across settings and data collection purposes, with a focus on any one or a combination of the three dimensions of sexual orientation—behavior, attraction, and identity. The complexities of categorizing sexual behaviors and erotic or romantic attractions present unique challenges to assessing sexual orientation. As a result, the panel does not offer recommended measures of the dimensions of behavior and attraction.

Sexual orientation identity is the cognitive as well as social expression of one’s sexual orientation. Thus, it is the dimension that is most

consistently tied to experiences with material forms of discrimination and most often invoked explicitly in laws and policies aimed at protecting (or harming) sexual minorities. It is also the dimension with the broadest and longest use in population-based data collection settings to enumerate and distinguish between sexual minority and majority adult populations. For these reasons, we focus our evaluation and recommendations on measures of sexual orientation identity.

RECOMMENDATION 2: The panel recommends that the National Institutes of Health use the following question for assessing sexual orientation identity:

Which of the following best represents how you think of yourself? [Select ONE]:

• Lesbian or gay
• Straight, that is, not gay or lesbian
• Bisexual
• [If respondent is AIAN:] Two-Spirit
• I use a different term [free-text]

(Don’t know)

(Prefer not to answer)

Table S-2 details a subset of selection criteria for our recommended measure.

The panel also recommends several areas for research, including validation of measures of sexual behavior and attraction and measures that incorporate “queer,” asexual, and other emerging identities; alternate wording for the “straight” response category; the utility of including community-specific terminology in response options; performance within adolescent populations; and how proxy reporting affects data quality (Recommendation 3).

TABLE S-2 Selected Evaluation Criteria for Recommendation on Sexual Orientation Identity

Gender Identity

Although many different strategies have been proposed for measuring gender identity, we focus on measures that allow for the enumeration of both transgender and cisgender people. We recommend using a “two-step” gender measure that includes both sex assigned at birth and a broad measure of gender identity because this approach is designed to include people with transgender experience who may not identify with the term “transgender”; it also replaces current nonspecific measures of sex/gender used in most data collection contexts.

RECOMMENDATION 4: The panel recommends that the National Institutes of Health use the following pair of questions for assessing sex assigned at birth and gender identity:

Q1: What sex were you assigned at birth, on your original birth certificate?

• Female
• Male

(Don’t know)

(Prefer not to answer)

Q2: What is your current gender? [Mark only one]

• Female
• Male
• Transgender
• [If respondent is AIAN:] Two-Spirit
• I use a different term: [free text]

(Don’t know)

(Prefer not to answer)

Table S-3 details a subset of the selection criteria for our recommended measure.

The panel also recommends areas for future research and question development, including the need for additional gender identity response options (e.g., nonbinary), alternative two-step measures that do not rely on sex assigned at birth, the effect of changes in the recording of sex on birth certificates, how proxy reporting affects data quality, and expanded testing among youth and non-English speakers (Recommendation 5).

TABLE S-3 Selected Evaluation Criteria for Recommendation on Gender Identity

Intersex/DSD Status

The measurement of intersex status is complicated by the unique experiences of intersex people and a limited research base. Biologically, intersex variations are highly heterogeneous, can involve any sex trait, and may not be apparent from an external examination. Most people with intersex traits are assigned male or female sex at birth. The majority of people with intersex traits are not identified as having an intersex variation until later in life—if at all. Intersex status is an important demographic characteristic and aspect of identity that also involves private medical information. While there are barriers to disclosure, people with intersex traits appear to want to disclose.

RECOMMENDATION 6: When the National Institutes of Health seek to identify people with intersex traits (differences of sex development) in clinical, survey, research, and administrative settings, they should do so by using a stand-alone measure that asks respondents to report their intersex status. They should not do so by adding intersex as a third response category to a binary measure of sex.

Unfortunately, there is very little evidence regarding the language or impact of measurement of intersex status in research, clinical, and administrative settings. Based on the available research, historical context, and community recommendations, there are three measures that appear to have the strongest grounding in evidence. Of these three measures, the panel prefers the following measure, because it is the only measure that has been tested among intersex populations—although it is potentially cumbersome to administer:

Have you ever been diagnosed by a medical doctor or other health professional with an intersex condition or a difference of sex development (DSD) or were you born with (or developed naturally in puberty) genitals, reproductive organs, or chromosomal patterns that do not fit standard definitions of male or female?

• Yes
• No

(Don’t know)

(Prefer not to answer)

In some situations, it might be necessary to identify a respondent’s specific intersex variation, and the panel recommends using the list of conditions developed by InterACT Advocates for Intersex Youth.

The panel also recommends that the National Institutes of Health fund or conduct research that comparatively evaluates the quality of the three measures of intersex status with the strongest grounding in the evidence to determine which measure most effectively identifies the intersex population. We further recommend research that tests the utility of including definitions and examples of terms used in intersex status questions, such as “intersex,” “DSD,” and specific intersex variations; examines the prevalence of “intersex” as a gender identity; and assesses proxy reporting of intersex/DSD status, particularly of parents reporting their children’s status (Recommendation 7).

The panel’s recommendations provide for consistent measurement of sex, gender, and sexual orientation across each data collection setting, while the research recommendations offer a detailed program that can refine these measures and ensure that they remain in step with cultural and historical developments. The consistent use of validated measures of these complex concepts and continued efforts to refine them will advance science that can be used to improve the well-being of sexual and gender minorities well into the future.