The study liberal friends are sharing: The Relationship Between Structural Racism and Black-White Disparities in Fatal Police Shootings at the State Level: https://www.sciencedirect.com/science/article/pii/S0027968417303206#bib23
In the study, the authors develop a "state racism index" based on 1. Residential segregation, 2. Incarceration rate gap, 3. Educational attainment gap, and 4. Employment disparity index.
Based on this index, they then compare fatal shootings of unarmed people. Results: "After controlling for numerous state-level factors and for the underlying rate of fatal shootings of black victims in each state, the state racism index was a significant predictor of the Black-White disparity in police shooting rates of victims not known to be armed (incidence rate ratio: 1.24; 95% confidence interval, 1.02-1.50). For every 10-point increase in the state racism index, the Black-White disparity ratio of police shooting rates of people not known to be armed increased by 24%."
They say they control for race-specific crime rates. I'm wondering how they were able to do that, and even if that is controlled for, isn't it still just correlation not causation? The correlation is interesting, but it doesn't convince me of systemic police racism. So what else could explain this correlation?