Black people and White people respond differently to social capital: what racial differential item functioning reveals for racial health equity.

Social capital has been conceptualized as features of social organization such as networks, and norms that facilitate coordination and cooperation for mutual benefit. Because of long-standing anti-Black structural oppression in the US, social capital may be associated with health differently for Black people than for other racial/ethnic groups. Our aim was to examine the psychometric properties of social capital indicators, comparing Black and White people to identify whether there is Differential Item Functioning(DIF) in social capital by race. DIF examines how items are related to a latent construct and whether this relationship differs across groups such as different racial groups. We used data from respondents to the Southeastern Pennsylvania Household Health Survey(SPHHS) in 2004 who lived Philadelphia(n=2,048), a city with a large Black population. We used Item Response Theory analysis to test for racial DIF. We found DIF across the items, indicating measurement error, which could be related to the way these items were developed-i.e., based on cultural assumptions tested in mainstream White America. Hence, our findings underscore the need to interrogate the assumptions that underly existing social capital items through an equity-based lens and taking corrective action when developing new items to ensure they are racially and culturally congruent.