It's about schools. Black Americans have worse education outcomes on average because of poverty, racial bias, unequal school funding and a culture where education is not as valued as with, say, Chinese Americans.
Saying this is something you need to "control for" is complete statistical nonsense. You wouldn't say "the accessibility in this building is better than average after controlling for wheelchair use".
They actually said that about education, so we are supposed to believe that eg black people are inherently less smart. I stopped reading their post before this tho :)
Can an American explain what this is supposed to be saying? Sounds like a right wing sound byte.
Are black people supposed to be inherently less healthy???