To be fair, it's probably true that the admit rate for MIT legacy applicants is also higher than the overall admit rate. It's just that the MIT admissions committee doesn't consider legacy status in admissions. It's hard to separate correlation from causation in the admit rates.
But these instututions explicitly have a preference for legacy applications, so we don't really need to work backwards from the correlation to the cause. They're telling us that they give preferential treatment to legacy applicants.
Difficult to do if you aren't even tracking what applications are legacy in the first place, they'd at least have to ask a sample of admitted and rejected students post facto.
