The Intersectional Discrimination Index: Development and validation of measures of self-reported enacted and anticipated discrimination for intercategorical analysis

Background and objective: Although intersectional approaches have gained traction in population health research, quantitative discrimination and health studies have tended to focus on a single axis of discrimination (e.g., racism, homophobia). As few discrimination measures function across multiple social identities or positions, we developed the Intersectional Discrimination Index (InDI) for intercategorical intersectionality research, including measures of Anticipated (InDI-A), Day-to-Day (InDI-D), and Major (InDI-M) discrimination that do not require attribution to particular grounds. Methods: We conducted a validity and reliability study with 2016 online survey panel data from Canada and the United States (n = 2583). Internal consistency and dimensionality of the InDI-A were evaluated with exploratory and confirmatory factor analyses. Construct validation included known-groups comparisons, associations with psychological distress, and convergence with existing discrimination measures. Test-retest reliability was examined in a subgroup (n = 150). Results: We found support for use of the InDI-A as a unidimensional scale. As hypothesized, racial and sexual/gender minorities reported higher frequencies of all discrimination types (all p < 0.001), and discrimination varied across intersectional categories. Each InDI component was significantly positively associated with psychological distress after controlling for potential confounders. Frequency scores were strongly positively correlated with existing scales. Intraclass correlation coefficients for test-retest reliability of anticipated, lifetime day-to-day, and lifetime major discrimination ranged from 0.70 to 0.72. Conclusions: Final InDI measures include the 9-item InDI-A, 9–item InDI-D, and 13-item InDI-M, for which we have found initial evidence of construct validity and reliability. In combination with sociodemographic information, the InDI measures can be used to evaluate the role of discrimination as a mediator of intersectional health inequalities, and to monitor the prevalence and impacts of discrimination in heterogeneous populations.