Diversity in research design

Sex and gender considerations in research

In line with the MESSAGE policy framework and the Medical Research Council (MRC) guidance on diversity in research design, applicants are expected to integrate sex and/or gender considerations into their research proposal wherever scientifically relevant. These requirements relate to the subjects of research (human participants, animals, human or animal tissues, cells, organoids, datasets, etc.).

Sex

Sex refers to the biological attributes which differentiate females and males, and which can include variations of what are considered female-typical and male-typical characteristics (sometimes known as “variations in sex characteristics” or “intersex”).

Gender

Gender refers to an aspect of a person’s identity. A person is subjected to a range of social forces (both constraints and privileges) based on their gender, which may influence their behaviours, their perception of themselves and how they are treated by others. All of these influences might be relevant for biomedical, health and care research.

For applicants

Applicants must clearly describe how sex and/or gender have been considered in their research design. Expectations differ slightly for preclinical and human research.

Studies involving animals, cells, tissues, or other preclinical models (sex only)

Applicants should include the following information:

1. Specify which sex(es) of animals, tissues, cell lines, or organoids will be included. Medical Research UK expects the use of both sexes as the default unless there is a clear, evidence‑based justification for using a single sex.
2. Provide the expected distribution of sexes and explain why this distribution is appropriate for answering the research question. There is no requirement to ‘balance’ or use equal numbers of different sexes.

The NC3Rs has developed a free online tool to guide researchers through the design of their experiments, helping to ensure that they use the minimum number of animals consistent with their scientific objectives, methods to reduce subjective bias, and appropriate statistical analysis.

Studies involving human participants or human‑derived data (sex, gender, and other diversity characteristics)

Applicants should include the following information:

1. Specify which sex and/or gender characteristics are relevant to the research question
2. Details of any planned sex- and/or gender-disaggregated analyses; or, if none are planned, a justification for why.
3. Outline the diversity characteristics of the population or subpopulations who could benefit from the research (e.g. age, ethnicity, socioeconomic status) and explain how considering these factors might contribute to improved health equity.
4. Describe how diversity and inclusion have been addressed throughout the research design (e.g. recruitment strategies, data collection, analysis) and explain why this approach is appropriate for the research question.

Researchers are expected to record and report relevant information about the diversity characteristics of research participants, so this is available even if these characteristics are not used in the analyses.

Justifying when sex and/or gender are not applicable

If sex and/or gender are not relevant to the research design, applicants should include the following information:

• A clear, scientific justification, and
• Evidence demonstrating that exclusion does not compromise the robustness, reproducibility, or applicability of the findings.