title: Disparities at the intersection of marginalized groups.
abstract: Mental health disparities exist across several dimensions of social inequality, including race/ethnicity, socioeconomic status and gender. Most investigations of health disparities focus on one dimension. Recent calls by researchers argue for studying persons who are marginalized in multiple ways, often from the perspective of intersectionality, a theoretical framework applied to qualitative studies in law, sociology, and psychology. Quantitative adaptations are emerging but there is little guidance as to what measures or methods are helpful.
  
  
  
  Here, we consider the concept of a joint disparity and its composition, show that this approach can illuminate how outcomes are patterned for social groups that are marginalized across multiple axes of social inequality, and compare the insights gained with that of other measures of additive interaction. We apply these methods to a cohort of young men from the National Longitudinal Survey of Youth, examining disparities for black men with low early life SES vs. white men with high early life SES across several outcomes that predict mental health, including unemployment, wages, and incarceration.
  
  
  
  We report striking disparities in each outcome, but show that the contribution of race, SES, and their intersection varies.
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, USA. john.jackson@mail.harvard.edu.
authors.forename: John W
authors.initials: JW
authors.lastname: Jackson
authors.affiliation: Department of Social and Biomedical Sciences, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Williams
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, USA.|Department of Biostatistics, Harvard T.H. Chan School of Public Health, 677 Huntington Avenue, Boston, MA, USA.
authors.forename: Tyler J
authors.initials: TJ
authors.lastname: VanderWeele
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D006801:Humans; D007182:Income / Q000706:statistics & numerical data*; D008137:Longitudinal Studies; D008297:Male; D011329:Prisoners / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D014478:Unemployment / Q000706:statistics & numerical data*; D044465:White People / Q000706:statistics & numerical data*; D055815:Young Adult
keywords: Attributable proportion; Decomposition; Disparities; Excess intersectional disparity; Heterogeneity of effects; Interaction; Intersectionality; Joint disparity; Ratio of observed to expected joint effects; Relative excess risk for interaction; Synergy index