Racial bias is a distortion arising from systemic, institutional, interpersonal or individual forms of explicit (conscious) or implicit (unconscious) prejudice against individuals or groups based on social constructs of race or ethnicity that influences the planning, methods, results, interpretation, dissemination and application of health research. As a flaw in research design that undermines the validity of results, research-based racial bias should be distinguished from everyday racial bias—a phenomenon characterised by unfair or harmful treatment of specific members of society.

Racial bias in research can take various forms, including the systemic under-representation of ethnic minorities (related to sampling and recruitment bias, impacting external validity), the use of non-validated methods or tools to analyse data from diverse populations (related to measurement bias and impacting construct validity),1 and the inappropriate interpretation of disparities in research findings due to the presentation of the social construct of race as biological and failure to recognise how it influences health outcomes (related to observer bias, confounding bias, confirmation bias, impacting internal validity).2 Racial bias can stem from systemic, institutional, interpersonal or individual forms of prejudice against a race or ethnicity. Prejudice can be explicit or implicit and can affect all stages of a health research project or study, through lack of diverse research teams and recruitment strategies, mistrust, language and cultural barriers,3 simplification of complex issues, convenience,4 or the legacy of incorrect beliefs about biological racial differences, historically used to justify white rule and systems of oppression.5

While the under-representation of racial and ethnic minorities in research studies is a commonly recognised issue, …